Angiotensin II neurotransmitter actions in paraventricular nucleus are potentiated by a nitric oxide synthase inhibitor.
There is increasing evidence that nitric oxide (NO) plays a role within the central nervous system as a novel messenger. Neuronal culture work suggests NO to be involved specifically in mediating actions of angiotensin II (ANG). The present study examined the potential role of NO within the paraventricular nucleus (PVN), a structure involved in mediating the cardiovascular changes initiated by activation of the subfornical organ (SFO). The pressor response to stimulation of SFO, which can be divided into a short (SD) and long duration (LD) component was enhanced following administration of an NO synthase inhibitor (L-NAME) (SD control: 101 +/- 4 vs. post L-NAME: 145 +/- 10 mmHg.s (P < 0.05); LD control: 387 +/- 167 vs. post L-NAME: 1737 +/- 617 mmHg.s (P < 0.05)). This effect was specific to activation of SFO efferents as the blood pressure responses to either, stimulation of PVN, or systemic administration of vasopressin were not potentiated by administration of L-NAME. These findings suggest that NO may be acting within PVN to inhibit further release of ANG, thereby attenuating the cardiovascular response to stimulation of SFO.
Bains
J S
JS
Department of Physiology, Queen's University, Kingston, Ontario, Canada.
Ferguson
A V
AV
D000594:Amino Acid Oxidoreductases / Q000037:antagonists & inhibitors*; D000804:Angiotensin II / Q000378:metabolism*; D000818:Animals; D001120:Arginine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects*; D004558:Electric Stimulation; D006339:Heart Rate / Q000187:drug effects; D008297:Male; D019331:NG-Nitroarginine Methyl Ester; D009569:Nitric Oxide / Q000502:physiology; D019001:Nitric Oxide Synthase; D010286:Paraventricular Hypothalamic Nucleus / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013356:Subfornical Organ / Q000187:drug effects / Q000502:physiology
D000804:Angiotensin II; D009569:Nitric Oxide; D001120:Arginine; D019001:Nitric Oxide Synthase; D000594:Amino Acid Oxidoreductases; D019331:NG-Nitroarginine Methyl Ester