Study of the effects of dopamine hydrochloride on alpha 1-adrenoceptors in rat kidney

We studied the number and affinity of catecholamine receptors in SD rat kidney by radioreceptor technique. The following conclusions were obtained: 1) By using 3H-prazosin, the numbers of alpha 1-receptor (Bmax) in rat renal cortex were greater than those in rat kidney medulla. As for affinity (Kd), the significance was not recognized between the two. Bmax of the rat renal cortex to 3H-prazosin binding was 96.1 fmol/mg protein, and Kd was 0.17 nM, and for the rat renal medullar these values were 44.5 fmol/mg protein and 0.13 nM, respectively. 2) By measurement of D1-receptor using 3H-SKF38393 in the rat renal cortex in the Scatchard plot analysis, positive cooperativity was observed under the low concentration of hot ligand which was less than 1 nM. But at the concentration of hot ligand over 1 nM, the plots showed a straight line. Bmax of the rat renal cortex to 3H-SKF38393 was 2.5 pmol/mg protein and Kd was 5.3 nM. 3) Based on displacement by dopamine for 3H-prazosin binding to rat renal cortex, it was surmised that high concentration of dopamine had an affinity to alpha 1-adrenoceptors. 4) There was no change in the Kd and Bmax of alpha 1-receptor in the rat renal cortex after incubation of samples with low concentration of dopamine. However, in the case of high concentration of dopamine, a remarkable decrease of the affinity (Kd) of alpha 1-adrenoceptor was observed.     

Bronchial venous plexus and its communication with pulmonary circulation

This study was undertaken to clarify the microvascular anatomy of the normal human bronchial circulation, focusing on the bronchial venous system and its communication with the pulmonary circulation. Ten normal lungs obtained at autopsy were studied. Bronchial arteriography was performed in six lungs, pulmonary arteriography in two lungs, and pulmonary venography in another two. Using radiologic methods, including microradiography, and serial histologic sections, we found numerous bronchial venous plexuses around the airways and blood vessels into which the bronchial capillaries drained. Frequent communications of the venous plexuses with the pulmonary veins and neighboring alveolar capillaries were also demonstrated. The bronchial venous plexus and its close connection with the pulmonary circulation may be important in various pathologic conditions involving the interstitial space, such as interstitial pulmonary edema.     

Ultrasonographic study on kidneys in patients with acute renal failure]

Ultrasonotomograms of 22 kidneys were obtained in 11 patients with renal-acute renal failure (renal-ARF). The underlying diseases of renal-ARF were acute tubular necrosis in 8 patients and acute on-set chronic glomerulonephritis in 3 patients. They were treated by hemodialysis in 10 patients and intermittent peritoneal dialysis in 1 patient. Ultrasonic measurement of the size of kidneys revealed that the thickness (anterior-posterior diameter) and the ratio of thickness to length (T/L) were greater in patients with ARF than in those with chronic renal failure and normal renal function. The patients with a low value of T/L (under 0.60) had a significantly greater urine volume than those with high a value of T/L (0.60 or more). The sonographic features of renal-ARF kidneys were marked increase in parenchymal echogenicity and appearance of hypoechoic swollen renal pyramids with sharpness of the corticomedullary border. In the course of ARF, these sonographic changes gradually disappeared when the patients had recovered from ARF. However, the prognosis was poor in patients with severer sonographic findings. We believe that repeated ultrasonic examination of the kidneys in patients with renal-ARF is useful for not only differential diagnosis of post-renal urinary obstruction but evaluating the course of ARF.     

Different types of relationship between beta-adrenergic relaxation and activation of cyclic AMP-dependent protein kinase in canine saphenous and portal veins

We examined the relationships between the relaxation mediated by beta-adrenoceptor and either the associated cyclic AMP production or the activation of cyclic AMP-dependent protein kinase (A-PK) in canine saphenous and portal veins. In the saphenous vein constricted with methoxamine, isoproterenol caused concentration-dependent relaxation (maximum relaxation 92.7%), and concomitant increases in cyclic AMP and A-PK activity ratio (from 52.8 to 73.5%). The portal vein was only slightly relaxed by isoproterenol (14.7% in the longitudinal strips) after constriction with methoxamine, while cyclic AMP and A-PK activation increased significantly. Isoproterenol markedly activated A-PK of the portal vein after KCl constriction (from 52.6 to 74.6%) but the maximum relaxation was only slight (13.3%). The portal vein also showed a smaller relaxation response to either forskolin or dibutyryl cyclic AMP than the saphenous vein. These results indicated that the relationship between the relaxation response to isoproterenol and either cyclic AMP production or A-PK activation was different in the saphenous and portal veins.     

Direct evidence of alpha-adrenoceptor binding in rat and human adrenal glands

In order to determine whether or not alpha-adrenoceptors are present in adrenal glands, radioligand receptor binding assay was performed in both Sprague-Dawley (SD) rat and human adrenal gland membranes. Radioligand binding assay using 3H-prazosin as an alpha 1-adrenoceptor ligand and 3H-yohimbine as an alpha 2-adrenoceptor ligand, clearly demonstrated alpha 1 and alpha 2 receptors present in both rat and human adrenal gland membranes. Maximal binding capacity (Bmax) and dissociation constant (Kd) of 3H-prazosin binding to the rat adrenal gland were 12.5 fmol/mg protein, and 0.11 nM, respectively. Those for the membrane preparations from adrenal cortex and medulla of the normal human were 16.3 fmol/mg protein, 0.34 nM and 16.3 fmol/mg protein, 0.27 nM, respectively. And those of the human pheochromocytoma were 25.6 fmol/mg protein, 0.15 nM, respectively. On the other hand, Bmax and Kd of 3H-yohimbine binding in the rat adrenal gland to were 22.9 fmol/mg protein, and 4.28 nM, respectively. Those for the membrane preparations from adrenal cortex and medulla of the normal human were 40.4 fmol/mg protein, 5.15 nM and 12.2 fmol/mg protein, 5.39 nM, respectively. And those of the human pheochromocytoma were 35.8 fmol/mg protein, and 1.08 nM, respectively. Bmax (35.8 fmol/mg protein) of 3H-yohimbine binding in the pheochromocytoma was significantly (p less than 0.01) greater than that (12.2 fmol/mg protein) in the human normal adrenal medulla, while Kd (1.08 nM) of this binding in the human pheochromocytoma was significantly (p less than 0.01) lower than that (5.39 nM) in the human normal adrenal medulla. Our data suggest that the alpha 2 receptor had greater affinity and binding site density to its agonist in the human pheochromocytoma than in the human normal adrenal medulla.     

Coronary artery bypass grafting with combined arterial grafts

Coronary artery bypass grafting with combined arterial graft using the left internal mammary artery (IMA), right IMA, and the right gastroepiploic artery (GEA) was performed in 45 patients with saphenous vein graft (SVG) (29 patients) or without SVG (16 patients) from February 1989 to October 1989. The left IMA was used in all patients, the right IMA was used in 9 patients, and the GEA was used in 43 patients. Perioperative myocardial infarction was noted in two patients who had hospital deaths. Reopening the chest for postoperative bleeding was performed in two patients, and the cerebral accident was noted in one patient. Fourteen patients were operated on without the requirement for blood transfusion. Studied within 3 postoperative months, all arterial grafts were patent though the patency was 97.7% (43/44) in SVG. It is concluded that the combined arterial graft utilizing the IMAs and GEA can be used safely and effectively.     

New hepatic vein reconstruction in left liver graft.

The incidence of hepatic venous stenosis is higher in partial liver transplantation. New methods for hepatic venous reconstruction in left liver transplantation, which secure wide anastomosis, were devised and are reported here. In the graft, the right side of the middle hepatic vein or the left side of the left hepatic vein was cut longitudinally and a rectangular-shaped vein patch was attached for venoplasty. In the recipient, after the left and middle hepatic veins were joined, the right side of the middle hepatic vein was cut toward the closed right hepatic vein, making a horizontal cavotomy for anastomosis. Of 92 patients who underwent conventional hepatic vein reconstruction, 3 were complicated by hepatic venous stenosis (median follow-up 43 months). By contrast, there were no hepatic vein complications in the 20 patients who underwent the new technique (7 months). The current method appears to be technically feasible for outflow reconstruction in left liver graft transplantation.