Regulation of calcium influx via voltage-dependent calcium channels (L-VDCC) into the vascular smooth muscle of genetically hypertensive rats

The present in vivo study was focused on better understanding of the pathophysiological mechanisms contributing to high blood pressure maintenance in spontaneously hypertensive rats (SHR). Genetic hypertension is characterised by abnormally elevated activity of sympathetic nervous system (SNS) and increased sensitivity to catecholamine-induced vasoconstriction comprising both enhanced calcium influx to vascular smooth muscle cells via L-type of voltage-dependent calcium channels (L-VDCC) and altered vascular sensitivity to intracellular calcium mediated by RhoA/Rho-kinase pathway. Thus, our aims were to study the regulation of L-VDCC channels, to determine the role of "calcium sensitization" in hypertension and finally to evaluate which of these pathways is important in the maintenance of high blood pressure. Using conscious SHR rats and their normotensive controls, WKY, we have confirmed that high sympathetic tone is responsible for increased calcium influx via L-VDCC in hypertension. The experiments based on the pertussis toxin-induced inactivation of inhibitory G proteins (Gi) have revealed that the control of L-VDCC by SNS is mediated by Gi protein- coupled pathway, the elimination of which leads to the attenuation of sympathetic vasoconstriction and to the decrease of blood pressure response to..