Localisation and characterisation of functional vasoactive intestinal peptide receptors in feline kidney

Specific ¹²⁵I-labelled vasoactive intestinal peptide (VIP) binding was determined in feline renal cortical and medullary plasma membranes. For the cortex, Scatchard analysis of the data resulted in a curvilinear plot with a high-affinity site K _0.5 of 8.4±2.6 nmol l^–1 (SE, n=6) and a second low-affinity site K _0.5 204 ± 16 nmol l^–1 with binding site concentrations (B _max) of 385±44.5 and 2710±181.3 fmol mg protein^–1 respectively. Conversely a similar analysis of the results obtained for outer medullary membranes gave a single site with a K _0.5 of 1.2±0.2 nmol l^–1 (SE, n=4) and B _max of 157.8±24.7 fmol mg^–1. Inner medullary membrane binding data. Gave a single site of lower affinity (K _0.5= 62.5±21.6 nmol l^–1; n=3). Structurally related peptides, glucagon and secretin, were ineffective (up to 1 mol l^–1) in displacing VIP from specific sites in both cortex and medulla. Porcine PHI 1–27 (a peptide having N-terminal histidine and C-terminal isoleucine) and a VIP antagonist [4-Cl-D-Phe⁶Leu¹⁷]VIP both displaced ¹²⁵I-VIP from cortical and medullary membrane binding sites with IC₅₀ values of 43.0 nmol l^–1 and 1.3 mol l^–1 (cortex) and 132.0 nmol l^–1 and 1.5 mol l^–1 (medulla) respectively. The localisation of specific VIP binding sites in feline kidney was investigated further by in vitro autoradiography. A high density of binding sites was visible at the cortico-medullary boundary as well as in the outer stripe of the outer medulla and in radial structures projecting into the cortex. There was a moderate density of binding sites in the superficial cortex. In addition the distribution of tubular VIP-sensitive adenylate cyclase was determined in microdissected nephron segments. In the presence of 10 mol l^–1 GTP, 1 mol l^–1 VIP effected marked stimulations over basal adenylate cyclase activity in medullary collecting tubules (4.7-fold), the bright and granular portions of the distal convoluted tubule (4.1- and 2.2-fold respectively) and in the pars recta of the proximal tubule (2.7-fold). Thus VIP-responsive adenylate cyclase has a discrete localisation in the feline nephron, which appears to correlate with specific binding sites as defined by autoradiography.     

Adenylate cyclase activity along the rabbit nephron as measured in single isolated segments

Summary A method is described, which allows adenylate cyclase activity measurement in single pieces of various nephron segments. Tubular samples of 0.5 to 2 mm length were isolated by microdissection from collagenase treated slices of rabbit kidney. A photograph of each piece was taken in order to measure its length. After a permeabilisation treatment involving preincubation in a hypoosmotic medium and a freezing step, each sample was incubated for 30 min at 30°C in a medium containing high specific [-³²P]-ATP 3·10^–4 M, final volume 2.5 l.The [³²P]-cAMP formed was separated from the other labelled nucleotides by filtering the incubate on a dry aluminium oxide microcolumn;³H cAMP was added as a tracer for measuring cAMP recovery. The sensitivity of the method was found to be a few fentomoles (10^–15 M) cAMP. cAMP generation increased linearly as a function of the incubation time up to more than 30 min, and as a function of the length of the segment used.Control and fluoride (5 mM) stimulated adenylate cyclase activities were measured in the following segments of the nephron: early proximal convoluted tubule (PCT), pars recta of the proximal tubule (PR), thin descending limb of the loop (TDL), cortical portion of the thick ascending limb (CAL), distal convoluted tubule (DCT), first branched portion of the collecting tubule (BCT), further cortical (CCT) and medullary (MCT) portions of the collecting tubule.Mean control adenylate cyclase activity varied from 7 (PR) to 75 (BCT) fmoles/mm/30 min. Fluoride addition resulted in a 10 (BCT) to 50 (PR) fold increase in enzyme activity.Series of replicates gave a scatter equal to ±20% (S.D. as a per cent of the mean).The method described appears to be suitable to determine which nephron segments contain hormone-dependent adenylate cyclase.This work was supported by a grant from the C.N.R.S. to the L.R.A. 219.     

Secretin and VIP-stimulated adenylate cyclase from rat heart

Cardiac adenylate cyclase activity was normal in 3 weeks-old spontaneously hypertensive rats of the Wistar-Okamoto substrain. The hormone-sensitive adenylate cyclase activity was reduced in 10 weeks-old or older animals, and secretin- and VIP-activations were definitely more impaired (by 64% and 69%, respectively) than isoproterenol- and glucagonactivation (17% and 22%, respectively). By contrast, the fluoride- and p[NH]ppG-stimulations of the enzyme were unaffected. These alterations in the adenylate cyclase system coupled to secretin and VIP appeared specific to the heart as the isolated pancreatic acinar cells from spontaneously hypertensive animals responded normally to secretin, as a liver particulate fraction responded normally to secretin and VIP, and both brain synaptic membranes and a particulate fraction of anterior pituitary to VIP.Abbreviations VIP vasoactive intestinal peptide - cyclic AMP cyclic adenosine 35-monophosphate - p[NH]ppG guanosine 5-(, -imido)triphosphate - EGTA ethylene-glycol-bis-(2-amino-ether)-N,N,N,N-tetraacetic acid - IBMX 3-isobutyl-1-methylxanthine     

Characterization of the VIP- and secretin-stimulated adenylate cyclase system from human lung

The response of a crude particulate adenylate cyclase preparation from surgically removed human lung to guanine nucleotides, sodium fluoride, -adrenergic agonists, prostaglandins, vasoactive intestinal peptide (VIP), secretin, and [Val⁵]secretin was investigated. The enzyme activity increased 5, 10, and 9-fold, respectively, with GTP, Gpp(NH)p, and sodium fluoride. This activity was stimulated (in the presence as well as in the absence of added GTP) byd,l-isoproterenol,l-epinephrine andl-norepinephrine, the relative potency of these agonists being compatible with the existence of -adrenoceptors of the -adrenoceptors of the ₂ subtype. Prostaglandins E₁ and E₂, but not PGF₁ and PGF₂, stimulated the enzyme, PGE₁ being at least 10 times more potent than PGE₂. The biphasic pattern of stimulation of the same adenylate cyclase activity by VIP suggested the presence of high- and low-affinity VIP receptors coupled to the enzyme. This stimulation by VIP was not inhibited by secretin-(7–27). The stimulation of adenylate cyclase by secretin and [Val⁵]secretin was also biphasic, suggesting the coexistence of high- and low-affinity secretin receptors. Secretin-(7–27) was able to inhibit completely the secretin stimulation acting through high-affinity secretin receptors but exerted no effect on the stimulation operating through low-affinity secretin receptors, which might indicate that the latter receptors were in fact VIP-preferring receptors. [Val⁵]secretin was also used to differentiate these peptide receptors, since its properties were more VIP-like than those of secretin.Abbreviations VIP vasoactive intestinal peptide - Sn secretin - cyclic AMP cyclic adenosine 3:5-monophosphate - Gpp(NH)p guanosine 5-O-(2-3-imido)triphosphate - EGTA ethylene glycol bis (2-aminoethyl ether)-N,N,N,N-tetraacetic acid     

The effect of vasoactive intestinal polypeptide (VIP) on forskolin stimulated adenylate cyclase in the caudate-putamen of the rat

Summary Vasoactive intestinal polypeptide (VIP) was incubated in an adenylate cyclase assay with a particulate fraction of caudate-putamen (CP) tissue of the rat in order to examine the effect of the peptide on forskolin-activated adenylate cyclase in vitro. Forskolin induced an enhancement of cyclic AMP formation that was mediated by an effect on catalytic subunit and stimulatory guanine nucleotide regulatory protein (N_s). In our preparation, VIP did not influence basal adenylate cyclase activity or the stimulation by dopamine and sodium fluoride but, in the absence of guanylylimidodiphosphate (guanosine 5-(,y-imido)-triphosphate) VIP inhibited the forskolin-stimulation of the enzyme in a noncompetitive manner. Met-encephalin, acting on a D-2 receptor-coupled putative inhibitory guanine nucleotide regulatory protein (N_i), inhibited the adenylate cyclase activity stimulated by forskolin to a slightly greater extent than VIP. When assayed together, these inhibition effects were additive, implying that the peptide receptors are not identical. The N_i — antagonist, MnCl₂ completely blocked the inhibition of met-encephalin but had no significant effect on VIP-induced inhibition. In addition, pertussis toxin did not influence the effect of VIP on forskolin-stimulation in contrast to cholera toxin which did antagonize the VIP effect via the stimulatory guanine nucleotide regulatory protein (N_s). Furthermore, specific D-1 and D-2 dopaminergic receptor antagonists (+)-flupentixol and spiperone had no effect on VIP-modulated forskolin-stimulated adenylate cyclase activity. These results suggest that the neuromodulatory effect of VIP is mediated by a N_s distinct from those involved in several adenylate cyclase pools sensitive to stimulation by dopamine and VIP in the rat striatum.     

Sites of thyroid hormone action on Na−K-ATPase along the rabbit nephron

Although Ismail-Beigi and Edelman demonstrated in 1971 that thyroid hormones control the activity of Na–K-ATPase in the mammalian kidney, the actual site of this regulation inside the organ was not located. We therefore decided to study the relationship between thyroid hormones and Na–K-ATPase activity in individual nephron segments obtained by microdissection of collagenase-treated rabbit kidneys. For this purpose, the changes in the activity and number of catalytic sites of Na–K-ATPase in response to thyroidectomy or triiodothyronine administration were examined. Eight to 12 days after thyroidectomy, Na–K-ATPase activity had dropped by 40 to 80% in the convoluted and straight portions of the proximal tubules, and in the cortical and outer medullary collecting tubules, but not in the thick ascending limbs of Henle's loops or distal convoluted tubules. The apparent number of catalytic sites for Na–K-ATPase, as measured by specific binding of³H-ouabain, decreased in parallel with Na–K-ATPase activity, and therefore this enzyme's specific activity was not altered. Fourty eight hours after injection of thyroidectomized animals with a single dose of either 100 or 500 g/kg triiodothyronine, Na–K-ATPase activity in target segments was restored to the level measured in control animals. These effects of thyroid hormone were specific for Na–K-ATPase, since the activity of adenylate cyclase, another marker of the basolateral membrane, was not altered by thyroidectomy. The results obtained indicate that triiodothyronine controls Na–K-ATPase activity in specific nephron segments, by altering the number of this enzyme's catalytic sites.Abbreviations PCT proximal convoluted tubule - PR pars recta - MAL medullary thick ascending limb of Henle's loop - CAL cortical thick ascending limb - DCT_b initial bright portion of the distal convoluted tubule - DCT_g granular portion of the distal convoluted tubule - CCT cortical collecting tubule - MCT outer medullary collecting tubule - TX thyroidectomized - T₃ triiodothyronine - AVP arginine vasopressin - PTH parathyroid hormone - ISO isoproterenol     

肠血管活性多肽调节多器官功能衰竭时肠黏膜肥大细胞的活性

目的　探讨肠血管活性多肽 (vasoactiveintestinalpeptide ,VIP)对多器官功能衰竭 (multi pleorganfailure ,MOF)时肠黏膜肥大细胞 (intestinalmucosalmastcells,IMMC)活性的调节及其病理生理意义。方法　酵母多糖腹腔注射法制作大鼠MOF模型 ,注射酵母多糖后 ,经尾静脉输入VIP(剂量为2 0pmol g体重或 0 .2pmol g体重 ) ,观察动物肠、肝、肾、肺等重要器官的组织病理改变及谷丙转氨酶ALT、肌酐Cr、血氧分压PO2 等功能指标变化 ,测定动物外周血和小肠组织组胺水平 ,透射电镜观察IMMC超微结构变化。结果　大剂量VIP输注后 ,与MOF对照组相比 ,大鼠各重要器官病变明显加重 ,ALT升高 [(180 .6 0± 2 3.4 0 )U Lvs (331.34± 35 .0 0 )U L],Cr升高 [(10 2 .35± 17.3)U Lvs 2 0 .5 0U L],PO2 降低 [(12 .5 4± 2 .6 0 )kPavs (7.4 4± 2 .17)kPa],P <0 .0 1,小肠组胺水平明显升高 [(8.4 0± 1.79)ng g体重vs (14 .30± 2 .70 )ng g体重 ,P <0 .0 1],IMMC脱颗粒现象明显改善。而小剂量VIP输注后 ,大鼠各重要器官病变明显减轻 ,ALT下降 6 2 .35 % ,Cr下降 6 3.2 0 % ,PO2 升高 38.30 % ,P <0 .0 1,小肠组胺水平明显降低 [(8.4 0± 1.79)ng g体重vs (4.70± 0 .4 5 )ng g体重 ,P <0 .0 1],IMMC脱颗粒现象更明显。     

肠血管活性多肽或生长抑素对大鼠肠淋巴细胞在肠淋巴组织分布的影响

目的：观察肠血管活性多肽（VIP）或生长抑素（SST）对大鼠肠淋巴细胞归巢至肠相关淋巴组织（GALT）的影响。方法：从肠系膜淋巴管插管引流淋巴液，淋巴细胞经VIP和SST体外孵育后，用^51Cr标记，将^51Cr-肠淋巴细胞朋股静脉回输入大鼠体内。取出各组织、器官，用γ计数器检测其放射性活度。结果：生理状况下，约10％^51Cr-肠淋巴细胞在短期内归巢至GALT。经VIP或SST孵育的^51Cr-肠淋巴细胞回输入大鼠体内后，在肠系膜淋巴结（1．85％，1．60％）用Peyer结（1.83%,1.56%)分布的百分比显著低于对照组（3．83％，3．85％），P＜0．05）。2种多肽对^51Cr-肠淋巴细胞在小肠弥散淋巴组织的分布无明显影响。结论：VIP或SST对大鼠肠淋巴细胞归巢至Peyer结和肠系膜淋巴结有一定的抑制作用。     

PTH sensitive adenyl cyclase activity in different segments of the rabbit nephron

Summary PTH sensitive adenylate cyclase activity was measured in 9 different segments of the nephron, isolated by microdissection from collagenase-treated rabbit kidney slices.The enzyme of the following segments was stimulated by PTH, 1 U/ml: PCT. (proximal convoluted tubule); PR (pars recta); CAL (cortical portion of the thick ascending limb); DCT (distal convoluted tubule); BCT (first, branched portion of the collecting tubule); the segments which did not respond to PTH were: TDL (thin descending limb); MAL (medullary portion of the thick ascending limb); CCT (cortical portion of the collecting tubule distally adjacent to BCT); MCT (collecting tubule from the outer medulla).PTH sensitive adenylate cyclase per mm tubule in PR was half that measured in PCT.Half maximal stimulation corresponded to 50–100 mU/ml PTH (1–2×10^–8M) in both PCT and PR, and to about 350 mU/ml in CAL. PTH (1 U/ml) stimulation factors ranged from 5 to 60 depending on the structures.It is concluded that in addition to PCT and PR, CAL and BCT might be target structures involved in the physiological actions of PTH on the kidney.This work was supported by a grant from the C.N.R.S. to the LRA n^o 219.     

Dopamine and somatostatin modulated adenylate cyclase activity in the rat caudate-putamen following unilateral cortical ablation

Summary Dopamine and somatostatin-14 (SRIF) were incubated with a membrane fraction of rat caudate-putamen (CP) tissue in an adenylate cyclase assay in order to examine the D-1-receptor coupled adenylate cyclase activity 5 days and 3 weeks after unilateral ablation of the left frontal and lateral cortex. Five days after decortication the ipsilateral basal and dopamine stimulated adenylate cyclase activity was increased by about 30% compared to that of the contralateral side. Three weeks after decortication no significant difference could be seen. On either side basal and dopamine stimulated adenylate cyclase activity was not significantly decreased compared to sham operated controls. Somatostatin (10^-7 mol/l) reduced basal adenylate cyclase activity of the ipsilateral CP five days following lesioning and reduced the maximal stimulation induced by dopamine. The effects of somatostatin were most marked in the absence and at low concentrations of dopamine (10^-7–10^-6 mol/l). The effects of somatostatin in the lesioned CP were no longer apparent three weeks following surgery. These results do not favour a presynaptic localization of D-1-receptors on cortico-striate projection fibers and suggest that somatostatin is involved in the interaction of the cortico-striate and nigro-striatal projection systems and may play a role in the regulation of D-1-receptor linked adenylate cyclase.     

Isotype-specific regulation of human lymphocyte production of immunoglobulins by sustained exposure to vasoactive intestinal peptide

Exposure of lymphocytes to nanomolar to micromolar concentrations of vasoactive intestinal peptide (VIP) for 1 to 3 days only modestly suppressed or enhanced the production of IgA and IgM, but not IgG. The effects of twice daily additions of 10⁻¹² to 10⁻⁷ mol/L VIP for up to 18 days on pokeweed mitogen- stimulated peripheral blood mononuclear cells (PBMCs) from normal human subjects was examined by quantifying the production of IgG, IgM, and IgA. The maximum suppression of IgG by 10⁻⁹ mol/L VIP was 79% ± 33% (mean ± SD) (range, 41 % to 97%; p < 0.015) on day 9 and 84% ± 1 % (range, 74% to 96%; p < 0.0001) on day 14 and was significant at 6 × 10⁻¹⁰ to 4 × 10⁻⁹ mol/L VIP. Suppression of IgM production by 10⁻⁹ mol/L VIP was significant and was observed first on day 5 and persisted through day 14. VIP did not alter IgA production or affect the proliferation or viability of PBMCs. The production of IgE by interleukin-4 stimulated PBMCs was enhanced consistently in two subjects but not in two other subjects. The duration of exposure to nanomolar concentrations of VIP is thus a critical determinant of its immunoregulatory effect, as manifested by late suppression of production of IgG and IgM and concurrent enhancement of production of IgE in some subjects.     

Catecholamine sensitive adenylate cyclase activity in different segments of the rabbit nephron

The sensitivity to catecholamines of the adenylate cyclase (AC) activity contained in single tubule samples was investigated on 10 different well defined segments, isolated by microdissection from collagenase treated rabbit kidneys. No responsiveness to isoproterenol (10(-6) M) was observed in the proximal tubule (convoluted and straight portions), the thin descending and thick ascending limbs of the loop of Henle, and the first ("bright") portion of the distal convoluted tubule (DCTb); in contrast high responses (stimulation factors: 4 to 6 fold) were obtained in the second ("granular") portion of the distal convoluted tubule (DCTg), as well as in both the "granular" (CCTg) and the "light" (CCTl) portions of the cortical collecting tubule. In absolute value, however, the CCTl response was definitely lower than those measured in DCTg and CCTg, as is its control activity. In the medullary portion of the collecting tubule, the AC response to isoproterenol was rather poor both in absolute and relative terms. Dose-response curves measured on DCTg samples indicated a threshold response with an isoproterenol concentration below 10(-8) M; half maximal effect corresponded to about 3 x 10(-8) M. CCTl sensitivity to isoproterenol was of the same order of magnitude. Isoproterenol as well as norepinephrine effects in DCTg and CCTl were completely suppressed by 10(-4) M propranolol, indicating that the observed AC stimulation was mediated via receptors of the beta type. In beta blocked CCTl, 10(-6) M norepinephrine did not inhibit vasopressin-induced AC stimulation; in the presence of 10(-6) M norepinephrine, 10(-4) M phentolamine resulted in no additional AC stimulation in DCTg and CCTl; these data suggest the absence of alpha receptors inhibiting AC activity in these structures. In DCTg, AC stimulation induced either by 10(-6) M isoproterenol or by 1 U/ml PTH were observed to be additive when the two hormones were given together. The presence of catecholamine-dependent AC activity in three distal portions of the rabbit nephron is discussed in relation to its possible physiological implications.     

Effects of somatostatin on dopamine sensitive adenylate cyclase activity in the caudate-putamen of the rat

Summary The effect of somatostatin-14 (SRIF) on dopamine-sensitive adenylate cyclase in caudateputamen pellets was studied in naive female rats, and in rats with chemical lesions of the nigrostriatal dopaminergic tract produced by injecion of 6-hydroxydopamine, or of the caudate-putamen itself produced by injection of kainic acid 3 week earlier. In unlesioned rats somatostatin at a concentration of 10^–7 moles/1 inhibited adenylate cyclase activation by submaximal concentrations of dopamine, increasing the apparent K_m but not altering E_max. In 6-hydroxydopamine lesioned rats somatostatin no longer influenced adenylate cyclase activity, whereas in kainic acid lesioned rats somatostatin still increased the apparent K_m for dopamine activation. The effect of somatostatin in untreated and lesioned rats is compatible with a partial competitive antagonism to dopamine. Although the data from the lesioned rats present preliminary results, the dose response characteristics and the effects in lesioned animals suggest a more complex interaction, possibly by binding of somatostatin to an inhibitory subunit of regulatory adenylate cyclase components.     

Impairment of Hormone-Stimulated cardiac adenylate cyclase activity in the genetically obese (fa/fa) Zucker rat

The age-related development of the capacity of the cardiac adenylate cyclase system to be stimulated with secretin, vasoactive intestinal peptide (VIP), glucagon, the β-adrenergic agonist isoproterenol, Gpp(NH)p, and NaF was compared in obese (fa/fa) Zucker rats and their lean (FA/?) littermates. The obese (fa/fa) Zucker rats tested developed postweaning obesity associated with marked hypertriglyceridemia, mild hyperglycemia, and hyperinsulinism. At 4 weeks, there was already a 57% reduction in secretin-VIP-stimulated adenylate cyclase activity in fa/fa rats. At 12 weeks, the secretin-VIP-stimulation was reduced by 77%, and glucagon-and isoproterenol-stimulations by 16–21%. At 45 weeks, secretin-VIP-stimulation was reduced by 91%, glucagon- and isoproterenol stimulations by 34–42%, and Gpp(NH)p- and NaF-stimulations by 16–23%. The reductions of isoproterenol-, Gpp(NH)p-, and NaF-stimulations were totally or partially reversed in 30-week old fa/fa animals submitted for 5 weeks to severe food restriction that almost normalized the altered blood parameters. In sharp contrast, food restriction imposed a further decrease in secretin-VIP- and glucagon-stimulated adenylate cyclase activities. This pattern of impaired secretin-VIP-stimulated adenylate cyclase activity appeared limited to cardiac membranes in obese animals as the responses of liver, brain and anterior pituitary adenylate cyclase activities to secretin and/or VIP were unaltered. These results suggest that secretin-VIP receptors coupled to adenylate cyclase were rapidly and specifically altered in the heart of fa/fa Zucker rats.     

Localization of kallikrein-like activity along a single nephron in rabbits

In order to investigate the presence of renal kallikrein, the localization of kallikrein-like proteolytic activity along a single nephron was determined in rabbits. Single nephrons were dissected into 8 segments under a microscope. Activity was fluorometrically measured with two different substrates (benzyl-l-arginine ethyl ester: BAEE and prolyl-phenylalanylarginine-methylcoumarin amide: MCA). Proteolytic activity could be detected in the early (S1), the middle (S2), and the terminal (S3) portions of the proximal tubule and in the granular portion of the distal tubule (DCTg). With MCA, the specific activity in S1, S2, S3 and DCTg was 0.77±0.08, 0.28±0.10, 0.13±0.05, and 0.27±0.05 pmoles/g/min, respectively. The activity in DCTg was inhibited by aprotinin but that in the proximal tubules was not inhibited. No activity was found in the glomerulus, the thick ascending limb of Henle's loop, the bright portion of the distal tubule, and the light portion of the cortical collecting tubule. The inhibition of the activity by aprotinin in DCTg suggests that intrarenal kallikrein could be localized only in DCTg.This research was presented in part at the 1st Asian Pacific Congress of Nephrology, Tokyo, 1979     

Topographical distribution of the secretin- and VIP-stimulated adenylate cyclase system in the heart of five animal species

Adenylate cylase stimulation by secretin and VIP was compared to the effect of glucagon,d,l-isoproterenol, Gpp[[NH]p, and NaF in atria and ventricles from rat, guinea pig, rabbit, dog and Cynomolgus monkey. In rat ventricular membranes, secretin was a better stimulant than VIP and was as active asd,l-isoproterenol. In rat auricular membranes both peptides were inactive. In guinea pig and rabbit heart membranes (ventricular and auricular) VIP and secretin were inactive. In dog and monkey atria, VIP stimulation of adenylate cyclase was comparable to that ofd,l-isoproterenol, secretin being inactive. In dog ventricules, VIP was less efficient thand,l-isoproterenol, secretin being inactive. In monkey ventricles, by contrast, VIP was slightly more efficient thand,l-isoproterenol, secretin having a small effect only in left ventricles. The present results established a clear difference between animal species with respect to the efficacy of the peptides of the secretin/VIP family: the presence of secretin-preferring receptors in rat heart contrasted with the presence of VIP-preferring receptors in dog and monkey heart. Our results in dog and monkey hearts suggest that VIP might be a candidate for a physiological control of heart function.Abbreviations VIP vasoactive intestinal peptide - Sn secretin - Gpp[NH]p guanosine 5-O-(2-3-imido) triphosphate - EGTA ethylene glycol bis (2-aminoethyl ether)-N,N,N,N-tetraacetic acid     

实验性糖尿病肺iNOS和VIP免疫组织化学观察及图像分析

目的:探讨糖尿病大鼠肺诱生型一氧化氮合酶(iNOS)及血管活性肠肽(VIP)的病理变化。方法:采用免疫组织化学方法,观察正常和四氧嘧啶诱导的糖尿病4周大鼠肺内iNOS及VIP的变化,并进行图像分析。结果:糖尿病4周大鼠肺支气管上皮细胞、肺泡管上皮细胞、肺泡囊上皮细胞和动脉内皮细胞iNOS呈阳性或弱阳性,静脉内皮细胞、毛细血管内皮细胞iNOS呈阴性。图像分析表明,糖尿病鼠肺iNOS的着色面积、积分光密度和相对含量均明显低于正常大鼠肺。糖尿病4周鼠肺支气管纤毛上皮细胞VIP呈阳性,支气管平滑肌肌层、支气管粘膜下腺体周围、肺间隔和肺动脉壁外膜VIP呈弱阳性或阴性,图像分析显示糖尿病鼠肺VIP着色面积、积分光密度和相对含量均明显低于正常大鼠肺。结论:糖尿病肺病变不仅受自主神经影响,而且非肾上腺素能非胆碱能神经改变亦与之有关,其神经递质NO和VIP可能在糖尿病肺病变中具有重要意义。     

Vasoactive intestinal peptide stimulation of renal adenylate cyclase and antagonism by (4Cl-d-Phe6Leu17)VIP

The effect of vasoactive intestinal peptide (VIP) and related peptides [glucagon, secretin, PHI 1-27 (peptide with N-terminal histidine and C-terminal isoleucine)] on renal adenylate cyclase (AC) has been determined in several species. The largest stimulation (4.1±0.5-fold basal) of AC by 1 mol · l^–1 VIP was observed in feline cortical plasma membranes. In rabbit and guinea-pig, VIP increased AC activity 1.5±0.3- and 1.8±0.3-fold respectively but glucagon had no such action. Conversely in the rat glucagon stimulated AC some 3-fold over basal activity whereas VIP had little effect. In dog, cat and mouse both peptides were effective in increasing AC activity. For cat, half-maximal stimulation of cortical plasma membrane AC by VIP was seen at 27.0±9.0 nmol · l^–1 (SEN=9 animals). VIP also increased AC activity in both outer (red) and inner (white) medulla. In feline cortical membranes VIP and PTH (parathyroid hormone) when added in combination were fully additive. However for VIP and glucagon in combination there was no cumulative increase in AC activity, indeed the resultant activity was less than that attained by VIP alone. The VIP analogue (4Cl-d-Phe⁶Leu¹⁷)VIP at 10 mol · l^–1 produced a right shift in the VIP-dose response curve and increased the EC₅₀ from 17.2±5.8 nmol · l^–1 to 132.0±22.2 nmol · l^–1 VIP (SEN=4). There was no reduction in the maximum response elicited by VIP consistent with a competitive type of antagonism by this analogue. PHI-stimulated AC was also reduced by (4Cl-d-Phe⁶-Leu¹⁷)VIP resulting in a similar right shift in the dose response curve. However, this analogue of VIP had no effect on glucagon- or secretin-stimulated AC, indicated by no change in EC₅₀ values.     

低氧对家兔局部脑血循环及脑组织中血管活性肠肽含量的影响

本实验观察了急性低氧及低氧习服家兔暴露于模拟海拔5000米低氧环境时局部脑血流量变化及脑组织中血管活性肠肽(简称VIP)含量变化。动物分为急性低氧组,低氧习服组和常压对照组。用脑电阻图法测定了家兔大脑皮层、下丘脑和海马三个部位的血流变化,用放射免疫分析法测定了以上部位组织中VIP的含量变化。结果表明,急性低氧可引起局部脑血流量增加,其幅度为42.6%～78.8%(P<0.05),但低氧习服动物三个部位血流量均无显著变化。急性低氧组脑组织VIP含量较对照有明显增加,大脑皮层VIP含量自对照107.9±8.3ng/s组织增至120.8±16.9ns/g组织,下丘脑自12.1±1.1ng/g组织增至21.1±2.9ng/g组织(P<0.05),海马VIP含量自对照的35.7±2.6ng/gTiss增至45.9±1.7ng/g组织(P<0.01),低氧习服组的VIP含量无显著变化。本实验结果提示,急性低氧可引起家兔脑组织中VIP含量增加,这一变化很有可能参与低氧时脑血流量的调节过程。     

Distribution of vasoactive intestinal polypeptide-, calcitonin gene-related peptide-, somatostatin- and neurofilament-immunoreactivities in sympathetic ganglia of human fetuses and premature neonates

The distribution patterns of vasoactive intestinal polypeptide (VIP), calcitonin gene-related peptide (CGRP), somatostatin (SOM) and neurofilament (NF) immunoreactivities (IR) were studied in the stellate ganglia of human fetuses and neonates at 24-26 weeks gestation. Sizeable populations with some quantitative variations of VIP-, CGRP- and SOM immunoreactive nerve cells were detected in all ganglia studied. In marked contrast, neurofilament expression was down-regulated. The upregulation of VIP, CGRP and SOM expression suggested their inductor effect on growth and differentiation neurons as well as on the development of their neurotransmitter properties. The main neuropeptides-inducing factor of sympathetic ganglia in human prenatal ontogenesis may be considered as a relative hypoxia.