RESUMO
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.
Assuntos
Pressão Sanguínea/fisiologia , Regulação da Expressão Gênica , RNA/genética , Receptores Purinérgicos P1/genética , Cloreto de Sódio na Dieta/farmacologia , Animais , Dieta Hipossódica , Modelos Animais de Doenças , Feminino , Hipertensão/metabolismo , Hipertensão/fisiopatologia , Masculino , Ratos , Ratos Endogâmicos Dahl , Receptores Purinérgicos P1/biossíntese , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
The in vitro differentiation of P19 murine embryonal carcinoma cells to neurons resembles developmental stages which are encountered during neuronal development. Three days following induction to neuronal differentiation by retinoic acid, most cells of the P19 population lost expression of the stage specific embryonic antigen (SSEA-1) and expressed the neural progenitor cell specific antigen nestin. Beginning from day 4 of differentiation nestin expression was down-regulated, and expression of neuron-specific enolase as marker of differentiated neurons increased. The molecular mechanisms underlying neuronal differentiation are poorly understood. We have characterized the participation of purinergic ionotropic (P2X) and metabotropic (P2Y) receptors at mRNA transcription and protein levels as well as ATP-induced Ca2+ transients during neuronal differentiation of P19 cells. Gene and protein expression of P2X2, P2X6, P2Y2, and P2Y6 receptors increased during the course of differentiation, whereas P2X3, P2X4, P2Y1 and P2Y4 receptor expression was high in embryonic P19 cells and then decreased following induction of P19 cells to differentiation. P2X1 receptor protein expression was only detected on days 2 and 4 of differentiation. Although P2X5 and P2X7 mRNA transcription was present, no protein expression for this receptor subunit could be detected throughout the differentiation process. In undifferentiated cells, mainly ionotropic P2X receptors contributed to the ATP-induced Ca2+-response. In neuronal-differentiated P19 cells, the ATP-induced Ca2+-response was increased and the metabotropic component predominated. Purinergic receptor function is implicated to participate in neuronal maturation, as cholinergic and glutamate-N-methyl-D-aspartate (NMDA) induced calcium responses were affected when cells were differentiated in the presence of purinergic receptor antagonists pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid (PPADS), suramin or reactive blue-2. Our data suggest that inhibition of P2Y1 and possibly P2X2 receptors led to a loss of NMDA receptor activity whereas blockade of possibly P2X2 and P2Y2 purinergic receptors during neuronal differentiation of P19 mouse led to inhibition of cholinergic receptor responses.