Evidence that alpha1A‐adrenoceptors control blood pressure in isolated rat mesenteric bed and their relationship with mRNA.

Abstract

Alpha1‐adrenoceptors participate in blood pressure control, where all three subtypes occur in blood vessels. However, it is known that one or two subtypes may be involved in arterial contraction. The aim of this work was to characterize the alpha1‐adrenoceptor subtype mediating muscular contraction in isolated mesenteric vascular bed and to determine the relative abundance of alpha1‐adrenoceptors mRNA.Eight week‐old, male Wistar rats were used in the study, after anesthesia mesenteric vascular bed was isolated and connected to a blood pressure transducer (BIOPAC). The tissue was perfused with Krebs solution and either A61603 or phenylephrine as alpha1‐adrenoceptor agonists and in the presence of alpha1‐adrenoceptor antagonists (RS100329, chloroethylclonidine and BMY 7378). In other set of experiments RNA from different regions of the mesenteric be was obtained and real time PCR. Results shown that alpha1A‐adrenoceptor subtype predominates for blood pressure control while alpha1D‐adrenoceptor mRNA predominates in distal and proximal regions of the arterial tree, while alpha1B‐ subtype was not modified. Data suggest a negative relationship between functional and molecular expression of alpha1‐adrenoceptors in rat mesenteric vascular bed. It will be interesting to measure alpha1‐adrenoceptor proteins to explain this apparent discrepancy.