title: Does vasopressin contribute to salt-induced hypertension in the Dahl strain?
abstract: A humoral factor has been implicated in Dahl salt-sensitive genetically hypertensive rats. The goal of this study was to evaluate the pressor role of vasopressin (AVP) in Dahl rats. Salt-sensitive (S) and resistant (R) rats were fed either high (8%) or low (.04%) NaCl diets for 6 to 8 weeks. Blood pressure was elevated in S rats fed high salt diets (p less than 0.05). Plasma AVP increased with high salt diet in both groups (p less than 0.05), but was higher in S than R rats (2.0 +/- 0.3 and 1.3 +/- 0.2 microU/ml respectively, mean +/- SE, p less than 0.05). With low salt diet, plasma AVP did not differ significantly in S and R rats (1.0 +/- 0.2 and 0.7 +/- 0.2 microU/ml respectively). Pressor responses to intravenous injection of AVP were greater in S than R rats (p less than 0.05), but this difference was also observed with pressor responses to norepinephrine (S greater than R, p less than 0.05); there was no difference in pressor responses to AVP in S rats fed high vs low salt diet. Injection of 50 micrograms of d(CH2)5 VDAVP, which selectively inhibits vasoconstrictor effects of AVP, failed to lower blood pressure in S and R rats fed high or low salt diets despite the fact that this dose decreased pressor responses to 8 microU of AVP more than 90%. Although plasma AVP and vasopressor responses to AVP and NE are slightly elevated in S rats fed high salt, results with d(CH2)5 VDAVP suggest that vasoconstrictor effects of AVP do not play an important role in the maintenance of hypertension in Dahl S rats.
mesh_terms: D000818:Animals; D001127:Arginine Vasopressin / Q000031:analogs & derivatives / Q000037:antagonists & inhibitors / Q000097:blood / Q000494:pharmacology; D004039:Diet, Sodium-Restricted; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006973:Hypertension / Q000139:chemically induced / Q000503:physiopathology*; D008954:Models, Biological; D051381:Rats; D011919:Rats, Inbred Strains / Q000235:genetics*; D012965:Sodium Chloride; D014661:Vasoconstriction / Q000187:drug effects
chemical_list: D001127:Arginine Vasopressin; D012965:Sodium Chloride; C016180:argipressin, Val(4)-