Endogenous bradykinin activity in Dahl rats.
We assessed the participation of endogenous bradykinin (BK) on basal blood pressure (BP) regulation in anesthetized Dahl-sensitive (DS) and Dahl-resistant (DR) rats receiving different NaCl diets. Four groups of Dahl rats were studied after 5 weeks of high (H) = 7% or low (L) = 0.4% NaCl diet (DSH, n = 9; DSL, n = 11; DRH, n = 9; DRL, n = 10). Endogenous BK activity was assessed with a continuous intraarterial (i.a.) infusion of the specific BK antagonist (B4146 100 micrograms/kg/min) for 10 min. Sensitivity to exogenous BK was tested 30 min after the end of the infusions, with bolus intraarterial (i.a.) injections of BK (0.1, 0.5, 1, and 5 micrograms). DSH had a significantly higher (p < 0.0001) basal mean BP (MBP) as compared with the three other groups: DSH = 185 +/- 7 mm Hg (mean +/- SEM), DSL = 143 +/- 5 mm Hg, DRH = 132 +/- 10 mm Hg, and DRL = 134 +/- 6 mm Hg. BK antagonist infusion increased MBP by 13.2 +/- 1.5 mm Hg in DSL rats, by 6.8 +/- 1.6 mm Hg in DRL, by 4.7 +/- 1.6 mm Hg in DRH, and by 1.1 +/- 8 mm Hg in DSH. Statistical analysis showed that the high NaCl diet significantly decreased the response to the BK antagonist in DS (p < 0.001) but not in DR rats. MBP response to exogenous BK was similar in all groups. These results show that endogenous BK has a vasodepressor effect on DS rats fed a low NaCl diet. This effect is suppressed after a high-salt diet.(ABSTRACT TRUNCATED AT 250 WORDS)
Benetos
A
A
INSERM U.337, Hôpital Broussais, Paris, France.
Bouaziz
H
H
Safar
M
M
D000704:Analysis of Variance; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D001920:Bradykinin / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors / Q000494:pharmacology / Q000502:physiology*; D005463:Fluoroacetates; D006339:Heart Rate / Q000187:drug effects; D007261:Infusions, Intra-Arterial; D008297:Male; D051381:Rats; D012982:Sodium, Dietary / Q000008:administration & dosage
D005463:Fluoroacetates; D012982:Sodium, Dietary; C050396:B 4146; D001920:Bradykinin