Role of phospholipids in the binding activity of vasoactive intestinal peptide receptors

Phospholipase digestion of rat intestinal epithelial cell membranes was performed in order to study the influence of membrane phospholipids on the binding activity of VIP receptors. Phospholipases A2 and C strongly (ED50 congruent to 4 X 10(-2) and 4 X 10(-1) micrograms/ml, respectively) and rapidly reduced 125I-VIP binding to membranes whereas phospholipase D was ineffective. This suggests an important role of both hydrophobic and hydrophilic groups of phospholipids on VIP receptor binding activity.     

Receptors for vasoactic intestinal peptide (VIP) in human colonic adenocarcinoma membranes: specific binding and stimulation of adenylate cyclase]

Human colonic adenocarcinoma plasma membranes exhibit specific receptors for VIP. Adenylate cyclase activity is stimulated by a VIP concentration as low as 10(-10) mol/1.     

Action of histamine and vasoactive intestinal peptide (VIP) on cyclic AMP in gastric glands isolated from human fetal stomach

Histamine and VIP produce an elevation of cAMP production in gastric glands isolated from the human fetal stomach at 15 weeks gestation. These effects were attributed to the activation of 2 distinct receptor-cAMP systems, one being sensitive to histamine in parietal cells, and the other being sensitive to VIP in muco-peptic cell populations. The results suggest that histamine and VIP may play a role in inducing gastric secretion during fetal life in man.     

Action of histamine and vasoactive intestinal peptide (VIP), on cyclic AMP in gastric glands isolated from human fetal stomach

Summary Histamine and VIP produce an elevation of cAMP production in gastric glands isolated from the human fetal stomach at 15 weeks of gestation. These effects were attributed to the activation of 2 distinct receptor-cAMP systems, one being sensitive to histamine in parietal cells, and the other being sensitive to VIP in muco-peptic cell populations. The results suggest that histamine and VIP may play a role in inducing gastric secretion during fetal life in man.     

Effects of dobutamine on cyclic AMP accumulation induced by the stimulation of dopamine receptors in rabbit retina in vitro

Summary Intact rabbit retinae were used for testing in vitro the potential activation of dopamine receptors by a new cardioactive sympathetic amine dobutamine. It was found that despite the structure relationship of dobutamine with other dopamine-analogs, the pharmacological action of this compound is not comparable to that of apomorphine, N-methyl-dopamine and/or ADTN.Acknowledgments. Supported by SNSF grant No. 3.327.078. The authors express their gratitude to Miss G. Allenbach for her excellent technical assistance and to Mr F. Pillonel for drawing the graphs.     

Effects of dobutamine on cyclic AMP accumulation induced by the stimulation of dopamine receptors in rabbit retina in vitro

Intact rabbit retinae were used for testing in vitro the potential activation of dopamine receptors by a new cardioactive sympathetic amine dobutamine. It was found that despite the structure relationship of dobutamine with other dopamine-analog, the pharmacological action of this compound is not comparable to that of apomorphine, N-methyl-dopamine and/or ADTN.     

Vasoactive intestinal peptide (VIP): specific receptors and adenylate cyclase activation in a human prolactin-secreting pituitary tumor]

Receptors for the Vasoactive Intestinal Peptide (VIP) were characterized in particles enriched in plasma membranes obtained from a human prolactin-secreting pituiatry tumor. Native VIP inhibited competitively the binding of 125I-VIP to the particles and stimulated cyclic AMP production; both these effects were observed at concentrations of VIP as low as 10(-11)-10(-10) M, which are compatible with VIP concentrations in the hypothalamopituitary portal blood.     

Interaction of vasoactive intestinal peptide (VIP) with cholinergic stimulation of glucagon secretion

Summary VIP-containing nerve fibers as well as cholinergic nerve fibers have a ubiquitous distribution in the body and both types of nerves have been demonstrated to innervate the pancreatic islets. The present study shows, in the intact, conscious mouse, that VIP and the cholinergic agonist carbachol stimulate glucagon secretion in a dose-dependent manner. Furthermore VIP and carbachol were found to exert potentiating interactions on glucagon secretion. These results suggest the existence of an interactive neural regulation of glucagon secretion, exerted by acetylcholine and VIP.We thank Professor V. Mutt, Karolinska Institutet, Stockholm, for giving us VIP. The skilful technical assistance of Lena K vist and Peter Okmark is gratefully acknowledged. This study was supported by grants from the Swedish Medical Research Council (14P-4289, 14X-4286) and the Medical Faculty, University of Lund, Sweden.     

Desensitization of adrenal tumor cells Y1 by ACTH and dibutyryl cyclic AMP]

The steroidogenic responsiveness of mouse adrenal tumor cell line (Y-1) to ACTH and db cAMP declines after stimulations by these compounds. The desensitization induced by ACTH appears early and is more pronounced than that induced by db cAMP. After removal of the hormone or the nucleotide, the recovery of cell responsiveness to both stimuli isprogressively restored. Full responsiveness is recovered within 24 hrs.     

Phosphorylase activity of human placenta perfused in vitro: effect of gonadotropins, dibutyryl cyclic AMP and prostaglandins]

The gonadotropic hormones stimulate the glycogen phosphorylase activity of human full-term placenta perfused in vitro. This effect is reproduced by dibutyryl cAMP and PG F2alpha and accompanied by an increased glucose liberation in the perfusion fluid.     

Changes in the concentration of vasoactive intestinal peptide in intestinal lymph in response to vagal stimulation in the calf

Summary Stimulation of both vagi caused a significant rise in arterial plasma vasoactive intestinal peptide (VIP) concentration in 3–5-week-old calves with cut splanchnic nerves. This was associated with a pronounced rise in the VIP concentration of intestinal lymph showing that vagal stimulation causes release of VIP from splanchnic viscera.Acknowledgment. This work has been supported by grants from the Agricultural Research Council and the Medical Research Council and we are indebted to Dr D.M. Burley (CIBA) for his continued support.     

Circadian variation of adrenocortical cyclic nucleotides (cyclic AMP and cyclic GMP) in hypophysectomized rats

The existence of a circadian variation in the adrenocortical concentrations of cyclic AMP and cyclic GMP in male adult Wistar rats examined 10 days after hypophysectomy is demonstrated. The results suggest that the circadian variations of adrenocortical cyclic nucleotides observed previously in intact rats might not entirely depend upon pituitary corticotrophin.     

Circadian variation of adrenocortical cyclic nucleotides (cyclic AMP and cyclic GMP) in hypophysectomized rats

Summary The existence of a circadian variation in the adrenocortical concentrations of cyclic AMP and cyclic GMP in male adult Wistar rats examined 10 days after hypophysectomy is demonstrated. The results suggest that the circadian variations of adrenocortical cyclic nucleotides observed previously in intact rats might not entirely depend upon pituitary corticotrophin.Acknowledgment. Thanks are due to Prof. J. M. Racadot and Dr Y. Drouet for their assistance with the histological examinations.     

Priming effect of vasoactive intestinal peptide on the respiratory burst of neutrophils non-mediated by plasma membrane receptors

Vasoactive intestinal peptide (VIP) primed the respiratory burst of human neutrophils in response to phorbol myristate acetate. Maximal and half-maximal effects were achieved at 10 and 0.5 nM VIP respectively. The absence of plasma membrane receptors to VIP in neutrophils suggests that priming of the respiratory burst should be considered as a side effect of VIP. However, from the above indicated concentration range, the priming of the neutrophil by VIP cannot be considered as a pharmacological effect. The enhancement of the formation of reactive oxygen metabolites by VIP may be important in the pathology of VIP-producing tissues.     

Demonstration of specific receptors for angiotensin III in rat adrenal glands]

Distinct and specific binding sites for 3H-angiotensin II (A II) AND 3H-angiotensin III (A III) have been demonstrated in Rat adrenal gland preparations. A III binding sites have the highest affinity (KD29C1-2.10(-10)M) for the 2-8 heptapeptide. This suggests the possibility of a separate and distinct physiological role for the 2-8 heptapeptide, mediated via such A III binding sites.     

Secretion of insulin and of glucagon by the perfused pancreas of newborn rats: effect of vasoactive intestinal peptide Vip]

A method is described for perifusion of the splenic part of the pancreas from 48-64 hour-old rat. In different basal conditions, the secretion of insulin and glucagon is stable and reproducible for 90 mn. The addition of the vasoactive intestinal peptide (VIP) to these perifusion media, at a concentration as low as 2 ng/ml, determines a remarkable increase of insulin and of glucagon secretion. These results suggest the possibility of a VIP action in the physiology of endocrine pancreas.     

Effect of dibutyryl cyclic AMP on cerebral energy charge and electrocorticographic activity in rats under asphyxic hypoxia]

In Rats anesthetized with pentobarbital and submitted to brief asphyxic episodes, intracerebroventricular administration of dibutyryl cyclic AMP inhibits the decrease of energy charge, delays the disappearance of electrocorticographic activity (E Co G) and shortens the recovery time of E Co G.