The area postrema in deoxycorticosterone-salt hypertension in rats.
Ablation of the area postrema in rats prevents sustained hypertension during angiotensin II infusion and after unilateral renal artery constriction (two-kidney, one clip hypertension). The current experiment was performed to determine whether an intact area postrema is required for hypertension development in a low renin model of experimental hypertension in rats. In 11 rats, the area postrema was destroyed using electrical current; the extent and specificity of each lesion was confirmed later by blind histological analysis. In 12 rats, sham operations were performed. All rats were uninephrectomized and drank saline. During once-weekly injections of deoxycorticosterone pivalate (5 mg/wk) for 4 weeks, sham-operated rats (n = 10) showed a significant increase in mean arterial pressure (Days 6-28) and saline intake (Days 12-28), but no significant increase in sodium or water retention. Deoxycorticosterone-treated rats with area postrema ablation (n = 9) exhibited no change in arterial pressure, sodium retention, or water retention, but a significant increase in saline intake (Days 17-28). Plasma renin activity was equally suppressed in both groups of rats. The depressor response to ganglion blockade with hexamethonium (20 mg/kg i.v.) was significantly increased during the 2nd, 3rd, and 4th weeks of steroid treatment in sham-operated, but not area postrema-ablated, rats. Four rats (2 sham-operated; 2 ablated) showed no change in any variable over 28 days in the absence of steroid treatment. It is concluded that the area postrema may be important in some non-angiotensin-dependent forms of experimental hypertension, possibly by affecting neurogenic control mechanisms.
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D001834:Body Water / Q000378:metabolism; D002552:Cerebral Ventricles / Q000502:physiology*; D003900:Desoxycorticosterone; D005730:Ganglionic Blockers / Q000494:pharmacology; D018738:Hexamethonium; D006584:Hexamethonium Compounds / Q000494:pharmacology; D006973:Hypertension / Q000139:chemically induced* / Q000503:physiopathology; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D012964:Sodium / Q000378:metabolism; D012965:Sodium Chloride
D005730:Ganglionic Blockers; D006584:Hexamethonium Compounds; D018738:Hexamethonium; D003900:Desoxycorticosterone; D012965:Sodium Chloride; D012964:Sodium