An Investigation into the Presence of a Vagal Tachycardia and the Effect of Vasoactive Intestinal Polypeptide on Rat Heart Rate in vitro

Pharmacology ◽  
2006 ◽  
Vol 76 (2) ◽  
pp. 101-104 ◽  
Author(s):  
K. Hogan ◽  
F. Markos
Keyword(s):  
Heart Rate ◽  
Vasoactive Intestinal Polypeptide ◽  
Rat Heart ◽  
Intestinal Polypeptide

scholarly journals Chronic atropine administration diminishes the contribution of vasoactive intestinal polypeptide to heart rate regulation

2008 ◽  
pp. 827-837
Author(s):  
J Kuncová ◽  
Š Faitová ◽  
J Capouch ◽  
M Štengl ◽  
J Slavíková
Keyword(s):  
Heart Rate ◽  
Single Dose ◽  
Vasoactive Intestinal Polypeptide ◽  
Rat Heart ◽  
Vagal Stimulation ◽  
Rate Regulation ◽  
Heart Rate Regulation ◽  
The Impact ◽  
Heart Atria ◽  
Intestinal Polypeptide

Vasoactive intestinal polypeptide (VIP) is implicated in the modulation of vagal effects on the heart rate. In this study, the impact of acute and chronic atropine administration on VIP levels in rat heart atria was investigated in relation to heart rate in the course of vagus nerves stimulation. Anaesthetised control and atropinised (10 mg/kg/day for 10 days) rats pretreated with metipranolol and phentolamine that were either given or not a single dose of atropine were subjected to bilateral vagus nerve stimulation (30 min: 0.7 mA, 20 Hz, 0.2 ms). VIP concentrations in the atria were determined after each stimulation protocol. In control rats with or without single atropine administration, the heart rate upon vagal stimulation was higher than in atropinised animals with or without single atropine dose, respectively. VIP concentrations in the control atria were significantly decreased after the stimulation; the decrease was comparable both in the absence and presence of a single dose of atropine. Compared to controls, VIP levels were significantly decreased after chronic atropine treatment and they were not further reduced by vagal stimulation and single atropine administration. Administration of VIP antagonist completely abolished the differences in the heart rate upon vagal stimulation between control and atropinised groups. In conclusion, the data indicate that chronic atropine administration affects VIP synthesis in rat heart atria and consequently it modifies the heart rate regulation.

scholarly journals Participation of vasoactive intestinal polypeptide in ovarian steroids production during the rat estrous cycle and in the development of estradiol valerate-induced polycystic ovary

Reproduction ◽  
2007 ◽  
Vol 133 (1) ◽  
pp. 147-154 ◽  
Author(s):  
Claudio Parra ◽  
Jenny L Fiedler ◽  
S Leticia Luna ◽  
Monika Greiner ◽  
Vasantha Padmanabhan ◽  
...  
Keyword(s):  
Estrous Cycle ◽  
Vasoactive Intestinal Polypeptide ◽  
Polycystic Ovary ◽  
Secretory Activity ◽  
Estradiol Valerate ◽  
Steroid Secretion ◽  
Cyclic Changes ◽  
Intestinal Polypeptide

Vasoactive intestinal polypeptide (VIP) stimulates estradiol and progesterone release from ovarian granulosa cells in vitro. Very little information is available as to the role VIP plays in the control of steroid secretion during reproductive cyclicity and in ovarian pathologies involving altered steroid secretion. In this study, we determined the involvement of VIP in regulating ovarian androgen and estradiol release during estrous cyclicity and estradiol valerate (EV)-induced polycystic ovarian development in rats. Our findings show that androgen and estradiol release from ovaries obtained during different stages of rat estrous cycle mimic cyclic changes in steroid release observed in vivo with maximal release occurring during late proestrus. VIP increased androgen release from ovaries of all cycle stages except late proestrus and estradiol release from all cycle stages. Increases in VIP-induced androgen and estradiol release were maximal at early proestrus. Inclusion of saturating concentrations of androstenedione increased magnitude of VIP-induced estradiol release at diestrus and estrus but not proestrus. Magnitude of VIP-induced androgen and estradiol release tended to be greater in the ovaries from EV-treated rats with polycystic ovary compared with estrous controls. At the tissue level, ovarian VIP concentration was cycle stage dependent with highest level seen in diestrus. Maximum concentration of VIP was found in EV-treated rats. Changes in VIP were inversely related to changes in ovarian nerve growth factor, a neuropeptide involved in ovarian androgen secretion. These results strongly suggest that intraovarian VIP participates in the control of estradiol secretion during the rat estrous cycle and possibly in the maintenance of increased ovarian estradiol secretory activity of EV-treated rats.

Reversal of nerve damage in streptozotocin-diabetic rats by acute application of insulin in vitro

1988 ◽  
Vol 75 (6) ◽  
pp. 629-635 ◽  
Author(s):  
Geoffrey Burnstock ◽  
Rhona Mirsky ◽  
Abebech Belai
Keyword(s):  
Vasoactive Intestinal Polypeptide ◽  
Calcitonin Gene Related Peptide ◽  
Diabetic Rats ◽  
Diabetic Rat ◽  
Rat Ileum ◽  
Related Peptide ◽  
Calcitonin Gene ◽  
Enteric Nerves ◽  
Intestinal Polypeptide

1. Immunohistochemical, immunoblotting and release experiments were performed on ileum from control rats, from 8-week streptozotocin-diabetic rats and from diabetic rats after acute application of insulin in vitro. 2. There was an increase in vasoactive-intestinal-polypeptide-like and a decrease in calcitonin-gene-related-peptide-like immunoreactivity in the myenteric plexus of the diabetic rat ileum, although electrically evoked release of both peptides from enteric nerves was defective. Acute application of insulin in vitro reversed the defective release and changes in immunoreactivity of vasoactive intestinal polypeptide and calcitonin-gene-related peptide seen in the enteric nerves of streptozotocin-diabetic rat ileum. 3. In addition, using a monoclonal neurofilament antibody RT 97 that recognizes a phosphorylated neurofilament epitope present in normal enteric nerves, it was shown that this phosphorylated neurofilament epitope was absent in diabetic nerves, even though a polyclonal neurofilament antibody revealed that neurofilaments were present in both axons and cell bodies of the myenteric plexus of diabetic rat ileum. After only 2 h of insulin incubation in vitro, the phosphorylated neurofilament epitope was again present in the nerves. 4. It is suggested that the abnormal distribution of phosphorylated neurofilaments and defective storage and release of vasoactive intestinal polypeptide and calcitonin-gene-related peptide in the present study may be a more general feature of diabetes. The restoration of these abnormalities by continuous acute insulin application in vitro shown here suggests that the availability of a steady level of insulin might prevent some of the changes which occur in early stages of diabetes. If so, this could influence the use of insulin in the treatment of diabetes, particularly in view of the recent report that short-term continuous subcutaneous insulin infusion restores the function of the autonomic and peripheral nerves in type I diabetic patients [Krönert, K., Hülsen, J., Luft, D., Stetter, T. & Eggstein, M. (1987) Journal of Clinical Endocrinology and Metabolism, 64, 1219–1223].

scholarly journals Vasoactive intestinal polypeptide in the PMSG-primed immature rat ovary and its effect on ovulation in the isolated rat ovary perfused in vitro

Reproduction ◽  
1990 ◽  
Vol 90 (2) ◽  
pp. 465-472 ◽  
Author(s):  
G. Schmidt ◽  
J. Jorgensen ◽  
P. Kannisto ◽  
F. Liedberg ◽  
B. Ottesen ◽  
...  
Keyword(s):  
Vasoactive Intestinal Polypeptide ◽  
Immature Rat ◽  
Rat Ovary ◽  
Isolated Rat ◽  
Intestinal Polypeptide

Serotonin stimulates vasoactive intestinal polypeptide release from rat hypothalamus in vitro

1983 ◽  
Vol 264 (1) ◽  
pp. 148-151 ◽  
Author(s):  
Akira Shimatsu ◽  
Yuzuru Kato ◽  
Norio Matsushita ◽  
Hideki Katakami ◽  
Hikaru Ohta ◽  
...  
Keyword(s):  
Vasoactive Intestinal Polypeptide ◽  
Rat Hypothalamus ◽  
Intestinal Polypeptide

Neural mediation of vasoactive intestinal polypeptide inhibitory effect on jejunal alanine absorption

1998 ◽  
Vol 275 (4) ◽  
pp. G822-G828 ◽  
Author(s):  
K. A. Barada ◽  
N. E. Saadé ◽  
S. F. Atweh ◽  
C. F. Nassar
Keyword(s):  
Vasoactive Intestinal Polypeptide ◽  
Myenteric Plexus ◽  
Inhibitory Effect ◽  
Dependent Manner ◽  
Sham Control ◽  
Extrinsic Innervation ◽  
Myenteric Plexuses ◽  
Intestinal Polypeptide

It was recently shown that vasoactive intestinal polypeptide (VIP) inhibits rat jejunal alanine absorption, an effect that was significantly reduced by vagotomy. This study assesses the role of capsaicin-sensitive primary afferents (CSPA) and the myenteric plexus in the inhibition of rat jejunal alanine absorption by VIP. Continuous intravenous infusion of VIP (11.2 ng ⋅ kg−1⋅ min−1) reduced alanine absorption by 60% in sham control rats and by 20% in rats neonatally treated with capsaicin ( P < 0.01). In in vitro experiments, VIP decreased alanine uptake by jejunal strips isolated from sham control rats in a dose-dependent manner. In the presence of 40 nM VIP, alanine uptake by full-thickness jejunal strips was reduced by 54% in sham control rats and by 25% in rats neonatally treated with capsaicin ( P < 0.001). On the other hand, VIP reduced alanine uptake by mucosal scrapings by 25% in sham rats compared with 9% reduction in neonatally treated rats. Chemical ablation of the extrinsic innervation and jejunal myenteric plexuses by pretreatment with benzalkonium chloride significantly ( P < 0.001) reduced basal alanine absorption and the inhibitory effect of VIP. Moreover, incubation of intestinal strips with tetrodotoxin and atropine reduced significantly ( P < 0.05) the inhibitory effect of VIP on alanine absorption. These data suggest that VIP exerts its inhibitory effect on alanine absorption through the CSPA fibers and the myenteric plexus. The neuronal circuitry of this inhibitory process may involve cholinergic muscarinic mechanisms.

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