The renal escape from the sodium retaining effect of mineralocorticoids in spontaneously hypertensive rats.
The effects of mineralocorticoids on urine and electrolyte excretion were studied in spontaneously hypertensive (SH) rats of Okamoto-Aoki strain and in normotensive white albino wistar strain rats. Sodium excretion fell from 0.568 meq/day to 0.336 meq/day a reduction of 40%, on the 4th day of steroid administration in the SH rats whilst a 30% reduction was observed on the 6th day in normotensive rats whilst urine volumes were not significantly altered in both groups. Similarly, the phase of acute sodium retention was reversed (renal escape) earlier in the SH rats on the 7th experimental day when further administration of mineralocorticoids resulted in a two-fold increased in sodium excretion. Urine volumes were significantly increased during this phase. The pattern of response in SH rats differ significantly in time and magnitude from the normotensive controls. As the renal escape phenomenon is linked with extracellular volume regulation these results highlight the exaggerated sensitivity to increases in blood volume associated with genetic spontaneous hypertension.
D000818:Animals; D003900:Desoxycorticosterone / Q000494:pharmacology; D004231:Diuresis / Q000187:drug effects; D005260:Female; D006854:Hydrocortisone / Q000494:pharmacology; D006973:Hypertension / Q000378:metabolism*; D007668:Kidney / Q000187:drug effects / Q000378:metabolism*; D008901:Mineralocorticoids / Q000494:pharmacology*; D011188:Potassium / Q000652:urine; D051381:Rats; D011919:Rats, Inbred Strains; D012964:Sodium / Q000378:metabolism* / Q000652:urine; D013997:Time Factors
D008901:Mineralocorticoids; D003900:Desoxycorticosterone; D012964:Sodium; D011188:Potassium; D006854:Hydrocortisone