Central nitrergic system regulation of neuroendocrine secretion, fluid intake and blood pressure induced by angiotensin-II.
BACKGROUND
Nitric oxide (NO) synthesis has been described in several circumventricular and hypothalamic structures in the central nervous system that are implicated in mediating central angiotensin-II (ANG-II) actions during water deprivation and hypovolemia. Neuroendocrine and cardiovascular responses, drinking behavior, and urinary excretions were examined following central angiotensinergic stimulation in awake freely-moving rats pretreated with intracerebroventricular injections of Nω-nitro-L-arginine methyl ester (L-NAME, 40 μg), an inhibitor of NO synthase, and L-arginine (20 ug), a precursor of NO.


RESULTS
Injections of L-NAME or ANG-II produced an increase in plasma vasopressin (VP), oxytocin (OT) and atrial natriuretic peptide (ANP) levels, an increase in water and sodium intake, mean arterial blood pressure and sodium excretion, and a reduction of urinary volume. L-NAME pretreatment enhanced the ANG-II response, while L-arginine attenuated VP and OT release, thirst, appetite for sodium, antidiuresis, and natriuresis, as well as pressor responses induced by ANG-II.


CONCLUSIONS
Thus, the central nitrergic system participates in the angiotensinergic responses evoked by water deprivation and hypovolemia to refrain neurohypophysial secretion, hydromineral balance, and blood pressure homeostasis.
Department of Physiology, School of Dentistry, Paulista State University of Araraquara, UNESP Araraquara São Paulo, Brazil.
Wagner L
WL
Reis
Wilson A
WA
Saad
Luiz A
LA
Camargo
Lucila Lk
LL
Elias
José
J
Antunes-Rodrigues
D000804:Angiotensin II / Q000008:administration & dosage / Q000819:agonists / Q000037:antagonists & inhibitors / Q000502:physiology*; D000818:Animals; D001120:Arginine / Q000008:administration & dosage / Q000494:pharmacology; D009320:Atrial Natriuretic Factor / Q000097:blood; D001794:Blood Pressure / Q000187:drug effects*; D001921:Brain / Q000187:drug effects / Q000502:physiology*; D004326:Drinking / Q000187:drug effects / Q000502:physiology*; D007276:Injections, Intraventricular; D008297:Male; D019331:NG-Nitroarginine Methyl Ester / Q000008:administration & dosage / Q000494:pharmacology; D009569:Nitric Oxide / Q000502:physiology*; D010121:Oxytocin / Q000097:blood; D051381:Rats; D017207:Rats, Sprague-Dawley; D017208:Rats, Wistar; D012964:Sodium / Q000378:metabolism; D014556:Urine / Q000502:physiology; D014667:Vasopressins / Q000097:blood
C472610:atrial natriuretic peptide, rat; D014667:Vasopressins; D000804:Angiotensin II; D009569:Nitric Oxide; D010121:Oxytocin; D009320:Atrial Natriuretic Factor; D001120:Arginine; D012964:Sodium; D019331:NG-Nitroarginine Methyl Ester