Withdrawal-induced antihypertensive effect of vasopressin: role of the L-arginine/nitric oxide pathway.

Abstract

The role of the endothelium-derived relaxing factor (EDRF), nitric oxide (NO), in the withdrawal-induced antihypertensive phenomenon (WAP) of arginine vasopressin (AVP) was studied in conscious unrestrained rats implanted with femoral arterial catheters for the measurement of arterial blood pressure. Cessation of a 3-h intravenous infusion of AVP (20 ng.kg-1.min-1) was followed by a large and long-lasting fall in mean arterial blood pressure below preinfusion control values in spontaneously hypertensive rats (SHR; -47.5 +/- 6.4 mmHg; 1 mmHg = 133.3 Pa) but not in normotensive Wistar-Kyoto (WKY) and Sprague-Dawley (SD) control rats. Chronic treatment of normotensive SD rats with the NO synthesis inhibitor, N omega-nitro-L-arginine (L-NNA; 0.5 g.L-1 in drinking water for 2 weeks), resulted in sustained hypertension. Similar to the SHR model, a large fall in blood pressure (-37.8 +/- 7.7 mmHg) was observed in this model of hypertension following cessation of the AVP infusion. In SHR, inhibition of NO synthesis with L-NNA (0.05 g.L-1 in drinking water for 2 weeks) failed to attenuate the fall in blood pressure following withdrawal of AVP. Chronic treatment with the NO precursor, L-arginine (L-Arg; 1.25 g.L-1 in drinking water for 2 weeks), did not affect the amplitude or the time course of the WAP in SHR. The results indicate that the L-Arg/NO pathway is not essential to the expression of the WAP to AVP in the SHR.

• Authors: R T Talom, J R McNeill
• Journal: Canadian journal of physiology and pharmacology (Can J Physiol Pharmacol) Vol. 75 Issue 7 Pg. 812-7 (Jul 1997) ISSN: 0008-4212 [Print] Canada
• PMID: 9315348 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Antihypertensive Agents
• Enzyme Inhibitors
• Vasoconstrictor Agents
• Arginine Vasopressin
• Nitroarginine
• Nitric Oxide
• Arginine

Topics

• Animals
• Antihypertensive Agents (pharmacology)
• Arginine (pharmacology, physiology)
• Arginine Vasopressin (pharmacology)
• Blood Pressure (drug effects, physiology)
• Enzyme Inhibitors (pharmacology)
• Hypertension (drug therapy, metabolism)
• Male
• Nitric Oxide (biosynthesis, physiology)
• Nitroarginine (pharmacology)
• Rats
• Rats, Inbred SHR
• Rats, Inbred WKY
• Rats, Sprague-Dawley
• Substance Withdrawal Syndrome (etiology, metabolism)
• Vasoconstrictor Agents (pharmacology)