Correlation of cholecystokinin receptors with gallbladder contractility in patients with gallstones.

The authors have previously identified two groups of patients with gallstones: those whose gallbladders contract the same as those of normal volunteers and show an increased sensitivity to endogenous cholecystokinin (CCK) ("contractors") and those whose gallbladders are relatively unresponsive ("noncontractors"). To define the mechanism responsible for these differences in contractility, the authors have measured CCK receptors on gallbladder muscle of patients with gallstones. Twenty-three patients with gallstones and 10 healthy volunteers (controls) fasted overnight. Simultaneous plasma samples for radioimmunoassay of CCK release and ultrasonographic measurements of gallbladder volume were obtained before and at intervals for 60 minutes after ingestion of Lipomul. Patients with gallstones had cholecystectomy, and CCK receptors were determined on cell membranes from gallbladder specimens by use of radiolabeled analogs of CCK-8-SO4. Histologic sections were graded for the degree of inflammation and scarring. Thirteen patients with gallstones were identified as contractors and 10 as noncontractors. Basal gallbladder volumes were not significantly different between patients in either group. The total integrated output of CCK for contractors was 1.6 +/- 0.2 ng X min/ml compared with 5.5 +/- 1.2 ng X min/ml for controls, while the integrated output for noncontractors was 11.1 +/- 2.1 ng X min/ml. Contractors had a higher number of CCK-binding sites (27.6 +/- 6.8 fmol/mg protein) than did noncontractors (4.8 +/- 1.0 fmol/mg protein). CCK receptors in gallbladders of all patients with gallstones correlated closely with gallbladder motility (y = 1.149, x = 0.624, r = 0.7, p less than 0.001). Although contractors had more mild inflammation and scarring, 40% of noncontractors had mild inflammation and scarring; there was no correlation. A decrease in CCK receptors may be an early event in the pathogenesis of gallstone formation by causing a decrease in gallbladder motility in some patients.     

Type II estrogen binding sites (EBS) in intracranial tumors

Four meningiomas and six neuroepithelial tumors were assayed for the presence of estrogen receptors (ER), type II estrogen binding sites (EBS) and progesterone receptors (PgR). ER were detected in 7 out of 10 cases with levels ranging between 2.5 and 20.7 fmoles/mg of cytosolic protein. On the contrary, PgR were found in all samples (10 cases) and their levels ranged between 8.8 and 130.6 fmoles/mg of cytosolic protein. All tumor samples expressed appreciable amounts of type II EBS ranging between 452 and 2320 fmoles/mg of protein. Although the precise functional role of type II EBS is still unknown, their presence may reflect an hormonal sensitivity of these tumors.     

Nifedipine inhibits cholecystokinin-induced gallbladder contraction

Nifedipine is a calcium channel blocker which results in relaxation of smooth muscle. Although it has been utilized clinically to treat cardiovascular disease, and more recently spastic disorders of the esophagus and colon, its effects on gallbladder contractility have not been clearly defined. We tested the effects of nifedipine on gallbladder contraction stimulated by cholecystokinin (CCK) in a conscious guinea pig model and in healthy human volunteers. Gallbladder contraction was measured in response to repeated injections of CCK before and after intravenous nifedipine given to groups of five guinea pigs in a dose of 100, 200, or 300 micrograms. Nifedipine virtually abolished spontaneous interdigestive gallbladder contractile activity and decreased resting gallbladder tone. The mean amplitude of gallbladder contraction in response to CCK was decreased by 45, 73, and 67% (P less than 0.01), in response to the nifedipine doses of 100, 200, and 300 micrograms, respectively. The integrated gallbladder contractile response and the rate of rise of gallbladder pressure in response to CCK were also significantly decreased by nifedipine. In nine healthy human volunteers, gallbladder emptying was measured by radionuclide cholescintigraphy in response to CCK infusion; on another day the study was repeated after oral administration of 10 mg nifedipine. Ejection fraction was significantly decreased by nifedipine from 72 +/- 5 to 51 +/- 5% (P less than 0.001). These data demonstrate that nifedipine is a potent inhibitor of gallbladder contractility in guinea pigs and man. This may provide the basis for the use of nifedipine clinically in the treatment of biliary colic and also raises questions about the potential effect of long-term nifedipine use on gallstone formation and cholecystitis.     

Evidence that the cholinergic enteropancreatic reflex may be independent of cholecystokinin release.

Studies were performed in four dogs with chronic gastric and pancreatic fistulas following intraduodenal perfusion with 10 mmole hr-1 of sodium oleate for 30 minutes. Radioimmunoassay (RIA) of plasma CCK LI was undertaken by an RIA method using labeled, desulfated CCK 8 I125 and an antiserum raised to CCK 8. The detection limit for the assay was 0.25 to 0.5 fmole and the lowest detectable plasma level was 5 to 10 fmoles ml-1. Since there was equal cross-reactivity to gastrin, a gastrin-specific assay also was employed to evaluate any changes in gastrin levels. After oleate infusion the plasma CCK increment above basal was 50 +/- 11 fmoles ml-1, with return to basal levels after 60 minutes. Administration of atropine significantly (P less than 0.01) inhibited the release of CCK in the first 20 minutes. Thereafter CCK release was not reduced. Plasma gastrin values did not change before and after oleate perfusion. Pancreatic protein output increased from 72 +/- 12 to 420 +/- 55 mg/10 min-1 after oleate administration. However, after atropinization the rise in pancreatic protein output was significantly lower (152 +/- 36 mg/10 min-1) (P less than 0.01). We have shown that, using our RIA method, there is a measurable rise in plasma CCK LI after intraduodenal oleate. After atropinization the CCK response was decreased significantly during the first 30 minutes, but was virtually unchanged during the second 30 minutes, when the fall in pancreatic protein output was most marked. We conclude that the cholinergic mechanism which plays a role in the endogenous stimulation of pancreatic protein secretion by intraduodenal oleate cannot be explained simply be decreased CCK release. This mechanism may be hormonal, distinct from secretin, or neural possibly, via activation of an enteropancreatic reflex.     

Comparison of the R-3327H rat prostatic adenocarcinoma to human benign prostatic hyperplasia and metastatic carcinoma of the prostate with regard to steroid hormone receptors

Quantitative analyses of cytosolic steroid hormone receptors were performed on nine tumors from the transplantable rat prostatic adenocarcinoma R-3327H. Androgen receptors and estrogen receptors were found in eight of nine and five of six tumors, respectively. None of the tumours analyzed contained detectable progestin or glucocorticoid receptors (four and seven tumors, respectively). The apparent equilibrium dissociation constants for the androgen and estrogen receptors were 0.7-4.3 nM and 0.6-1.8 nM, respectively. The apparent equilibrium Bmax values (maximum number of binding sites) were 1,500-25,000 fmoles/gm tissue for the androgen receptor and 640 to 5,800 fmoles/gm tissue for the estrogen receptor. A comparison between the receptor contents of the R-3327H rat tumor and human benign prostatic hyperplasia and metastatic carcinoma of the prostate showed that the rat tumor was different from the human tissues in several respects. Hence, the search for an optimal animal model for prostatic carcinoma in man must be continued.     

Arris & Gale lecture. Regulation and responses of gallbladder muscle activity in health and disease

A complex relationship links biliary symptoms with the mechanisms of gallbladder emptying and the presence of gallstones. This relationship has been investigated by clinical studies of symptoms associated with gallstones, by investigation of gallbladder emptying and cholecystokinin (CCK) release in patients with gallstones, and after cholecystectomy, or truncal vagotomy, and in the irritable bowel syndrome (IBS). Laboratory studies examined receptor density on bovine gallbladder, and contractility of human gallbladder in response to a variety of stimuli was studied in vitro. A set of six symptoms associated with the presence of gallstones was identified; IBS appeared to be present in two-fifths of patients before cholecystectomy but only one-third of these patients had persistent IBS symptoms one year after operation. Gallbladder emptying studies confirmed the poor contraction of stone-bearing gallbladders; abnormal patterns of emptying were also found in patients with IBS. Gallbladder emptying and filling appear to be largely neurally regulated. CCK receptor density was very low in gallbladder tissue, suggesting that receptors on nerve cells might mediate the action of CCK. Relaxation of gallbladder muscle was mediated by adrenergic and nitrergic nerves. The inflammatory mediator bradykinin, however, had a strong direct action on muscle cells to cause gallbladder contraction. The work reported here gives an overview of the symptoms and mechanisms of disease associated with the presence of stones in the gallbladder.     

Relationship between gallbladder contraction and progesterone receptors in patients with gallstones

Stasis of bile within the gallbladder has long been suspected of having an important role in the pathogenesis of gallstone disease. We postulated that the female preponderance of gallstone disease might partly be related to the effects of progesterone, a known smooth muscle relaxant, on specific receptors in the gallbladder wall, leading to stasis of bile. A total of 42 patients with gallstone disease and 28 control subjects underwent radionuclide scan imaging and their gallbladder ejection fractions were calculated in response to intravenous infusion of cholecystokinin octapeptide. Patients then underwent cholecystectomy and a piece of gallbladder fundus was assayed for the presence of progesterone receptors. Receptors were present in 60 percent of patients. As a group, gallstone patients had a decreased ejection fraction compared with control subjects. The presence of progesterone receptors in the gallbladder wall was associated with a decreased percentage of ejection compared with both healthy control subjects and patients whose gallbladders were receptor-negative. We conclude that progesterone receptors are present in the gallbladder wall of gallstone patients and that their presence correlates with impaired gallbladder emptying.     

Estrogen and progesterone receptors in normal and varicose saphenous veins.

The presence of estrogen and progesterone receptors was investigated in the walls of normal and varicose veins. Cryostat sections from the saphenous veins of 29 normal individuals, and varicose and normal vein segments of 32 patients with varicose veins, were stained with anti-estrogen or anti-progesterone receptor antibodies. Nuclear stain intensity was scored by three independent observers. Receptors to both hormones were detected in the nuclear regions of the intima and media in females and males. In the adventitia, estrogen and the progesterone receptors were found only in nuclei of the vasa vasorum. Estrogen receptor levels were lower in non-varicose segments of varicose veins compared with normal veins. In varicose segments, estrogen receptors were more abundant than in the non-varicose parts of the same vein, especially in females. Similarly, progesterone receptor levels in the non-varicose portions were higher in females. These gender differences may be related to hormonal action. However, these differences may also be age related. These findings may be related to the involvement of sex-hormones in varicosis, by mechanisms as yet unknown.     

The role of neurotensin in human gallbladder motility.

Gallbladder contraction in response to a fatty meal is thought to be caused by release of cholecystokinin (CCK). We have previously demonstrated a close correlation between circulating concentrations of CCK and contraction of the gallbladder in normal humans and in gallstone patients. Recent studies in animals, however, have shown that other potentially cholecystokinetic hormonal agents are released by a fatty meal, which suggests that other hormones may be involved in postprandial gallbladder contraction. Neurotensin, a 13-amino acid peptide, is released by fat; we have shown it to cause gallbladder contraction in dogs. In the present study, we measured release of neurotensin in seven normal adult volunteers. We determined the effects of infused neurotensin (4 pmol/kg-min) on gallbladder contractility, measured by ultrasonography in 10 adult volunteers, and we evaluated release of neurotensin in eight patients with gallstones. After ingestion of fat, we found significant release of neurotensin in normal volunteers from a mean basal concentration of 15.9 +/- 3.5 pg/ml to a maximum of 34.7 +/- 0.2 pg/ml. In the gallstone patients after fat ingestion, neurotensin rose from a basal of 16.8 +/- 3.1 pg/ml to a maximum of 53.4 +/- 28.1 pg/ml, which was a significantly greater release than in controls. Intravenous infusion of neurotensin produced dilatation of the gallbladder (from a mean basal volume of 13.7 +/- 2.3 cc to 20.0 +/- 1.8 cc). Neurotensin causes relaxation of the gallbladder in humans and, by contributing to stasis, may be involved in the formation of gallstones.     

The effect of estrogen-replacement therapy on clitoral-cavernosal tissue in oophorectomized rats: a histo-quantitative study by image analyzer

Sexual dysfunction is an important problem for aging females. However, little attention has been paid to female sexual dysfunction. The clitoris is an important organ for physiological sexual function in females. There is a close relationship between the presence of sexual complaints and levels of estrogen. Using the rat as an experimental model, we evaluated the effect of estrogen-replacement therapy and its timing on clitoral-cavernosal collogen fiber content after oophorectomy. Four-month-old female Wistar rats (n = 36) weighing 230-250 g were used. They were categorized into four groups: oophorectomized (Group 1: n = 10); oophorectomized delayed estrogen replacement (group 2: n = 10); oophorectomized + immediate estrogen replacement (group 3: n = 10); and sham operated (group 4: n = 6). The estrogen replacement used was 17-beta-estradiol. All rats were euthanized at the same age. The specimens were stained with Masson's trichome technique, and computerized image analysis was used to quantify the collagen-fiber content of clitoral-cavernous tissue. The clitoral collagen-fiber percentages in the different groups were as follows: group 1: 64.17 +/- 5.01%; group 2: 62.57 +/- 5.37%; group 3: 56.33 +/- 3.85%; group 4: 51.48 +/- 6.37%, respectively. Although there was a tendency in the untreated group for a higher collagen-fiber content, no statistically significant difference was found among groups (P > 0.05). Although the results of this study were not statistically significant, estrogen did appear to decrease clitoral-cavernosal collagen-fiber content. These findings may be important in the pathophysiology of postmenopausal female sexual dysfunction.     

Effect of chronic atropine administration on the rat urinary bladder

Micturition is accomplished via a coordinated contraction of the urinary bladder body mediated primarily by muscarinic receptor stimulation. Theoretically, bladder function may be modified by pharmacologically altering either the muscarinic receptor density and/or the magnitude of the response to receptor activation. In the central nervous system, autonomic receptor density can be modified by chronic administration of specific receptor agonists and antagonists. The chronic administration of receptor agonists induces a decrease in the specific receptor density whereas the chronic administration of antagonists induces an increase in the specific receptor density. Although these induced alterations in receptor density occur in the CNS, there have been few studies on peripheral tissue. For the current study, we have administered L-atropine chronically to rats (five mg./kg./day) using implanted osmotic pumps. Using direct radioligand binding techniques, the muscarinic receptor density of the rat brain (cortex) and urinary bladder were determined following six hours, 12 hours, one, two, four, seven, 11 and 14 days of atropine administration. In addition, we have also determined the effect of atropine administration on bladder weight and the response of isolated strips of the bladder to bethanechol, a specific muscarinic agonist. For both the brain and the bladder, the receptor density increased progressively and reached a maximum by seven days. At 14 days of atropine administration, the density of muscarinic receptors in rat brain increased significantly (p less than .05) from 2956 +/-74 fmoles/mg. protein to 3800 +/-170 fmoles/mg. protein. The muscarinic receptor density of the rat urinary bladder increased significantly from 115 +/-10 fmole/mg. protein to 165 +/-14 fmole/mg. protein. Although there was a 42% increase in bladder mass, the contractile response of isolated strips to bethanechol did not change significantly. This study demonstrates that the urinary bladder can respond to the chronic administration of atropine with a significant increase in the density of muscarinic receptors. The magnitude of the increase observed was slightly greater than the magnitude observed for muscarinic receptors isolated from the brain cortex.     

Effects of female sex hormones and pregnancy on gallbladder prostaglandin synthesis

To investigate whether female sex hormones and pregnancy induce increased gallbladder synthesis of prostaglandin I2 (PGI2) and prostaglandin E (PGE), we used an in vitro incubation chamber to quantitate the effects of progesterone, estrogen, pregnancy, and pregnancy plus a 2%-cholesterol diet on mucosal and serosal PGI2 and PGE production by the rabbit gallbladder. Neither the female sex hormones nor pregnancy alone caused a significant increase in PGI2 or PGE synthesis. The gallbladders of cholesterol-fed, pregnant rabbits demonstrated significant increases only in serosal synthesis of PGI2. This increased production was equivalent to that noted for gallbladders from nonpregnant rabbits fed a high-cholesterol diet. There were no increases in mucosal synthesis of PGE or of PGI2. Thus, neither elevated levels of progesterone or estrogen nor pregnancy is directly responsible for the increased PGI2 activity in the female gallbladder; conversely, this effect seems to be mediated by the increased biliary concentrations of cholesterol.     

Comparison of cholecystokinin release and gallbladder emptying in men and in women at estrogen and progesterone phases of the menstrual cycle

Why are gallstones more common in women than in men? To investigate this, we measured gallbladder emptying (by ultrasonography) and release of endogenous cholecystokinin (CCK) (by specific radioimmunoassay) in eight men and nine women in response to ingestion of corn oil (1 gm/kg). Each woman was studied on the fourteenth and twenty-first day of her menstrual cycle, estimated to be the estrogen (women [E] ) and progesterone (women [P] ) peaks, respectively. Fasting plasma concentrations of CCK were significantly higher in women (E) (135 +/- 7 pg/ml) than in men (99 +/- 13 pg/ml) but not significantly higher than in women (P) (113 +/- 11 pg/ml). The peak increase in CCK concentration over basal concentration and the integrated release of CCK were not significantly different from one group to another. Men had a larger fasting gallbladder volume (GBV) (21.4 +/- 3.2 ml) than did women (E) (12.4 +/- 2.1 ml) and women (P) (14.2 +/- 2.1 ml) and emptied more GBV in response to fat than did the women. The residual GBV and fractional emptying after ingestion of corn oil were not different among the three groups. Measurements of plasma CCK and GBV during the contraction phase were highly correlated in all groups. It appears, from these data, that the increased prevalence of gallstones in women relative to men cannot be explained on the basis of significant differences either in release of CCK or in gallbladder motility. Linear regression lines that were developed indicated that the mean change in GBV relative to a given change in plasma CCK was significantly higher in men than in women. Differences between men and women in this hormonal-motility relationship may contribute to the incidence of gallstones in premenopausal women.     

Effect of operative devascularization on estrogen and progesterone receptor levels in breast cancer specimens

To compare estrogen and progesterone receptor values between biopsy and mastectomy specimens, we prospectively studied 29 patients with breast cancer treated by incisional biopsy followed by mastectomy. The average tumor size was 5.4 +/- 0.5 cm and the mean age was 57.6 +/- 3.0 years. Nine patients were premenopausal and 20 were postmenopausal. Biopsies were performed without electrocautery, and tissue samples were promptly frozen and subsequently assayed for estrogen and progesterone receptor levels. After mastectomy, samples of residual tumor were excised from the biopsy site, promptly frozen, and assayed for estrogen and progesterone receptor levels. Operating time averaged 87.7 +/- 6.0 minutes. Estrogen receptor levels averaged 100.0 +/- 24.4 femtomole per mg on biopsy specimens and 29.5 +/- 8.2 fmol/mg on mastectomy specimens, representing a 70% decline (p less than 0.02). Of clinical significance is the fact that eight of 29 (27.6%) tumors changed from positive estrogen receptor values in the biopsy specimen to negative (four) and borderline (four) in the mastectomy specimens. Progesterone receptor levels were more variable, but their mean value decreased by 24.4% from 17.6 +/- 6.4 fmol/mg on biopsy samples to 13.3 +/- 4.3 fmol/mg on mastectomy samples (p, not significant). We conclude that the biopsy specimen is usually a more reliable indicator of hormonal receptor status than the mastectomy specimen and recommend that incisional or excisional biopsy specimens be taken for estrogen and progesterone receptor assays before mastectomy.     

Different phenotypes generated by changes in bcl-2 and p53 expression in breast cancer

We have identified by immunohistochemistry/ immunocytochemistry the expression of bcl-2 molecule in 55 primary breast carcinomas and in 30 corresponding axillary lymph nodes metastases, together with a set of molecules known as prognostic factors: estrogen receptors, progesterone receptors, and p53 protein. Our results demonstrated a significant correlation (p < 0.05) between bcl-2 and hormonal receptors expression in tumors, but not in axillary metastases (p < 0.1), a significant inverse correlation between bcl-2 and p53 expression in primary tumors (p < 0.02), but a significant direct correlation in axillary metastases (p < 0.02). The bcl-2+/p53- phenotype, associated with normal breast epithelium, is present in 79.17% primary tumors, but only in 15.38% axillary lymph nodes metastases. A larger number of lymph nodes metastases expressed a bcl-2+/ p53+ more aggressive phenotype compared with primary tumors (58.82% versus 48.39%). This shows that changes in the expression of bcl-2, p53, estrogen and progesterone receptors can lead to an increased cellular aggressiveness and thus to an increased tumoral invasive and metastasizing potential.     

Androgen binding in the baboon prostate.

Androgen receptors were identified and partly characterized in cytosols of the caudal and cranial prostatic lobes of a 24-hr castrate baboon. Binding of cyproterone acetate (CA) to testosterone-binding globulin (TeBG) in baboon serum was negligible and therefore was an appropriate unlabeled competitor for distinguishing high-affinity binding of tritiated dihydrotestosterone (3H-DHT) to serum contaminants and receptors in cytosol preparations when multiple-point saturation analyses and removal of free steroid by charcoal adsorption were used. Specificity of androgen binding was demonstrated by the inability of diethylstilbestrol, a synthetic estrogen known to have low binding affinity for TeBG, to displace 3H-DHT from the receptor protein. The number of high-affinity binding sites and the dissociation constant of the androgen receptor calculated for the caudal lobe were 102 fmoles/mg cytosol protein and 4.0 X 10(-9) M, respectively; corresponding values for the cranial lobe were 49 fmoles and 1.3 X 10(-9) M.     

Delayed plasma cholecystokinin and gallbladder responses to intestinal fat in patients with Billroth I and II gastrectomy

This study was undertaken to examine the intestinal phase of cholecystokinin (CCK) secretion and gallbladder contraction in patients who had undergone partial gastrectomy. Plasma CCK concentrations, measured by radioimmunoassay, and gallbladder contraction, measured by cholescintigraphy, were studied after intestinal administration of fat. Fasting plasma CCK concentrations were in the same range in nine patients who had undergone Billroth I gastrectomy (1.0 +/- 0.2 pmol/L), in nine patients who had undergone Billroth II gastrectomy (1.4 +/- 0.2 pmol/L), and in nine normal subjects (1.5 +/- 0.4 pmol/L). The peak increments in plasma CCK after intestinal fat were significantly (p less than 0.05) lower in patients with partial gastrectomy (5.4 +/- 0.6 pmol/L) compared with normal subjects (7.9 +/- 0.8 pmol/L). The integrated plasma CCK secretion was significantly (p less than 0.01 to p less than 0.05) reduced during the first 30 minutes in patients after Billroth I (74 +/- 11 pmol/1.30 min) and Billroth II gastrectomy (51 +/- 11 pmol/1.30 min) compared with normal subjects (122 +/- 18 pmol/1.30 min). Similarly, the start of gallbladder emptying was significantly (p less than 0.05) delayed in patients after partial gastrectomy. After 1 hour, however, the integrated plasma CCK response and gallbladder emptying were in the same range in Billroth I patients (186 +/- 34 pmol/1.60 min, 60% +/- 7%), Billroth II patients (175 +/- 17 pmol/1.60 min, 63% +/- 7%) and normal subjects (190 +/- 18 pmol/1.60 min, 55% +/- 6%). It is concluded that in patients who have undergone partial gastrectomy plasma CCK and gallbladder responses to intestinal fat are significantly delayed but reach normal levels beyond 30 minutes.     

Decreases in renal functional reserve and proximal tubular fluid output in conscious oophorectomized rats: normalization with sex hormone substitution

Age-dependent glomerulosclerosis with reduced GFR develops earlier among men than among women. Therefore, whether female sex hormones could prevent the age-dependent decrease in GFR was investigated. The kidney function in oophorectomized rats treated with placebo (OOX group), estrogen (OOX+E(2) group), or estrogen plus progesterone (OOX+E(2)+P group) for 5 mo and in sham-operated rats (sham group) was examined. The rats were 13 mo of age at the time of the investigation. They were conscious and chronically instrumented. The results demonstrated that estrogen, alone or in combination with progesterone, was without effect on the baseline GFR and effective renal plasma flow but prevented severe decreases in the renal functional reserve and fractional proximal tubular fluid output (lithium clearance technique, fractional lithium excretion), which were observed in the OOX group. The renal functional reserve (estimated by stimulation with glycine) was -223 +/- 151, 483 +/- 129, 675 +/- 76, and 208 +/- 140 micro l/min in the OOX, OOX+E(2), OOX+E(2)+P, and sham groups, respectively. Fractional lithium excretion was 12.4 +/- 3.1, 26.8 +/- 2.0, 31.8 +/- 2.5, and 23.6 +/- 3.3% in the OOX, OOX+E(2), OOX+E(2)+P, and sham groups, respectively. In conclusion, oophorectomy at the age of 8 mo did not produce a decrease in baseline GFR in female rats within a period of 5 mo. However, oophorectomy led to severe decreases in the renal functional reserve and fractional proximal tubular fluid output. Both effects were prevented with administration of estrogen. Sham-operated rats demonstrated values for renal functional reserve and fractional lithium excretion that were between those observed for the OOX group and the groups treated with sex hormones.     

Correlation of release and actions of cholecystokinin in dogs before and after vagotomy

Pancreatic secretion of enzymes and gallbladder contraction in response to intestinal stimulants are thought to be mediated through the vagus nerve and by means of release of cholecystokinin (CCK). The effect of truncal vagotomy on the release of CCK, pancreatic protein secretion, and gallbladder pressure (all stimulated by intraduodenal instillation of oleate) was studied in five dogs. Each dog was prepared with chronic pancreatic and gastric fistulas and catheter cholecystostomies. Simultaneous measurements were made of plasma CCK (by radioimmunoassay), pancreatic protein secretion, and gallbladder pressure (by perfused catheter technique) before and during intraduodenal administration of oleate. Before truncal vagotomy, intraduodenal oleate caused increases in plasma CCK (from 82 +/- 6 to 208 +/- 32 pg/ml), pancreatic protein secretion (from 83 +/- 8 to 165 +/- 15 mg/15 min), and gallbladder pressure (from 11 +/- 2 to 27 +/- 2 cm H2O) (all measured from basal state to 120 minutes). Truncal vagotomy caused a 45% decrease in the output of pancreatic protein in response to oleate and completely abolished the increase in gallbladder pressure, but it caused no change in release of CCK. The correlations between plasma CCK and pancreatic protein secretion before truncal vagotomy (r = 0.86) and after truncal vagotomy (r = 0.77) were highly significant. The correlation between plasma CCK and gallbladder pressure was highly significant before (r = 0.91) but not after (r = 0.42) truncal vagotomy. This study demonstrates that truncal vagotomy inhibits pancreatic protein secretion and gallbladder pressure in response to fat but does not interfere with release of CCK. The effects may be due to interruption of vagus-mediated reflexes between the intestine and the pancreas and gallbladder. The good correlation between plasma concentrations of CCK and both pancreatic protein secretion and gallbladder pressure provides evidence that the radioimmunoassay measures biologically active CCK.     

Activity of angiotensin peptides in clitoral cavernosum of alloxan induced diabetic rabbit

OBJECTIVES: To assess the role of peptides of the angiotensin (ANG) on the regulation of clitoral cavernosum tone and changes in ANG binding affinity in the rabbit with diabetes mellitus. MATERIAL AND METHODS: The isometric tension measurement and in vitro autoradiography were used in sham and diabetic clitoral cavernosum. RESULTS: In tension study, contractility in response to ANG I, ANG II, ANG III and ANG IV was enhanced in diabetic clitoral cavernosum strips (EC50 was 67.6 +/- 27.2, 4.3 +/- 0.4, 189.3 +/- 37.3, 443.2 +/- 0.4 nM for diabetic versus 155.2 +/- 76.1, 38.3 +/- 0.1, 528.0 +/- 75.2, 616.9 +/- 69.5 nM for sham, respectively). Contractile responses to ANG II was significantly inhibited by type 1 ANG II receptor (AT1) antagonist but not by type 2 ANG II receptor (AT2) antagonist in both groups. Percentages in contractions by ANG II (1 nM) in the presence of Dup 753 decreased significantly 36.2 +/- 4.6 to 6.3 +/- 2.4% in sham and 56.1 +/- 7.7 to 6.0 +/- 4.8% in diabetic group. The binding affinities were enhanced in diabetic clitoral cavernosum for ANG II (dissociation constant, 4.9 +/- 1.0 for sham versus 0.9 +/- 0.2 nM for diabetic) and for ANG I, ANG III, and ANG IV (inhibitory constant, 28.6 +/- 1.5, 398.7 +/- 157.2, and 3966.5 +/- 1524.1 nM for sham versus 20.6 +/- 5.7, 78.5 +/- 23.7, and 1098.7 +/- 195.5 nM, for diabetic, respectively, all p < 0.05). Sensitivities of AT1 and AT2 receptors to ANG II enhanced in diabetic than sham clitoral cavernosum tissue. CONCLUSIONS: This results suggest that the contractile responses to all four ANG peptides are enhanced in the diabetic clitoral cavernosum. Enhancement of contractility in diabetic clitoral cavernosum may be related to the increased affinity to ANG II receptors for ANG peptides.