Acidosis reduces the function and expression of ?1D-adrenoceptor in superior mesenteric artery of Capra hircus.

ABSTRACT: The objective of this study was to characterize the ?1-adrenoceptor (?1-AR) subtypes and evaluate the effect of acidosis on ?1-AR function and expression in goat superior mesenteric artery (GSMA).GSMA rings were mounted in a thermostatically controlled (37.0°C ± 0.5°C) organ bath containing 20 ml of modified Krebs-Henseleit solution, maintained at pHo of 7.4, 6.8, 6.0, 5.5, 5.0, and 4.5. Noradrenaline (NA)- and phenylephrine (PE)-induced contractile response was elicited in the absence or presence of endothelium and prazosin at pHo of 7.4, 6.0, and 5.0. The responses were recorded isometrically by an automatic organ bath connected to PowerLab and analyzed using Labchart 7.1.3 software. Expression of ?1D-AR was compared at physiological and acidic pHo using reverse transcription-polymerase chain reaction (RT-PCR).NA- and PE-induced contractile responses were attenuated proportionately with a decrease in extracellular pH (pHo), i.e. 7.4 ? 6.8 ? 6.0 ? 5.5 ? 5.0 ? 4.5. Endothelium denudation increased the contractile response at both normal and acidic pHo. Prazosin (1 nM, 10 nM, and 0.1 ?M) inhibited the NA- and PE-induced contractile response at pHo 7.4 and the blocking effect of prazosin was potentiated at pHo of 6.0 and 5.0. RT-PCR analysis for ?1D-AR in GSMA showed that the mRNA expression of ?1D-AR was decreased under acidic pHo as compared to physiological pHo.(i) Adrenergic receptor mediates vasoconstriction in GSMA under normal physiological pHo, and ?1D is the possible subtype involved in this event (ii) acidosis attenuates the vasocontractile response due to reduced function and expression of ?1D-AR and also increased the release of endothelial-relaxing factors.

SUBMITTER: Mohanty I 

PROVIDER: S-EPMC4980928 | biostudies-literature | 2016 Jul-Aug

REPOSITORIES: biostudies-literature