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.
Reis
Wagner L
WL
Department of Physiology, School of Dentistry, Paulista State University of Araraquara, UNESP Araraquara São Paulo, Brazil.
Saad
Wilson A
WA
Camargo
Luiz A
LA
Elias
Lucila Lk
LL
Antunes-Rodrigues
José
J
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