Relationship between baroreflex sensitivity, renin suppression and natriuresis in salt-sensitive rabbits.
This study determined the influence of baroreflex sensitivity (BRS) on the rate of urinary sodium excretion and plasma renin activity (PRA) in response to a saline infusion in conscious male rabbits specifically bred for high (Group I; n = 7) and low (Group II; n = 10) BRS and in seven control animals. Only Group II showed significant increases in blood pressure on a chronic high-salt intake. After ensuring that each animal was in sodium balance, a (0.7-0.9%) saline infusion of 3-4 ml/kg per h for 90 min (25% daily sodium intake for each rabbit) was given and urine collected at 15-min intervals via a bladder catheter. No differences were found in control urine volumes, urinary sodium or PRA. Group I excreted over 50% of the sodium load and Group II less than 20% within 90 min. PRA fell by more than 30% within 30 min in six Group I rabbits but decreased by less than 30% or increased in Group II. In the control animals, sodium excretion rates and PRA suppression were also much greater in those with high BRS. A highly significant correlation (r = 0.808, P less than 0.01) was found between the per cent of the sodium load excreted and BRS. It is suggested that the delayed sodium excretion and blood pressure elevation in salt-sensitive subjects may be due to a genetic impairment in baroreflex control of renal sympathetic nerve activity.
Weinstock
M
M
Department of Pharmacology, Hebrew University-Hadassah Medical School, Jerusalem, Israel.
Borosh
M
M
Kafri
O
O
Kaczmarczyk
G
G
D000818:Animals; D005919:Glomerular Filtration Rate / Q000502:physiology; D006339:Heart Rate / Q000502:physiology; D006400:Hematocrit; D007262:Infusions, Intravenous; D008297:Male; D009318:Natriuresis / Q000502:physiology*; D011311:Pressoreceptors / Q000502:physiology*; D011817:Rabbits; D012083:Renin / Q000097:blood*; D012982:Sodium, Dietary / Q000008:administration & dosage / Q000493:pharmacokinetics*; D013045:Species Specificity
D012982:Sodium, Dietary; D012083:Renin