Adenosine Receptors Influence Hypertension in Dahl Salt-Sensitive Rats: Dependence on Receptor Subtype, Salt Diet, and Sex

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Abstract

The influence of adenosine receptors on blood pressure in salt-sensitive hypertension is unknown. Here, we examined the effects of salt diets on arterial blood pressures (radiotelemetry) in female and male Dahl salt-sensitive wild-type versus female and male Dahl salt-sensitive A1, A2A, or A2B receptor knockouts (A1KOs, A2AKOs, and A2BKOs, respectively). At baseline, all rats were on a 0.3% salt diet; then separate groups were switched to either 4% or 8% salt diet for 2 weeks. Compared with wild-types, baseline pressures were not affected by knockout of A1 or A2B receptors; yet, mean, systolic, and diastolic pressures were significantly (P<0.01) higher in A2AKOs versus wild-types, an effect independent of sex. During the second week on a 4% salt diet, mean, systolic, and diastolic blood pressures (mm Hg, mean±SEM) in female A1KOs (176±5, 209±5, and 147±4, respectively) and A2BKOs (166±8, 198±9, and 139±8, respectively) were significantly lower (P<0.001) than wild-type on a 4% salt diet (202±4, 240±5, and 172±3, respectively). Male A1KOs and A2BKOs were not protected against 4% salt diet–induced hypertension. This female advantage was overwhelmed by an 8% salt diet. Female and male A2AKOs were more salt sensitive, a phenotype that was apparent in male A2AKOs on 4% and 8% salt diets and in females on 8% salt diet. Female A1KOs and A2BKOs were less susceptible to salt-induced stroke and experienced improved survival. Adenosine receptors influence blood pressure and survival in salt-sensitive rats, and the impact of deleting adenosine receptors on blood pressure and survival depends on salt diet and sex.

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