TRPV4 activation in rat carotid artery in DOCA hypertension involves eNOS and endothelium-derived contractile factor (EDCF)

Abstract

Aim: Role of TRPV4 channel in regulation of endothelial function in the carotid artery in deoxycorticosterone acetate (DOCA) model of hypertension in rat was studied. Methods: 8–10 weeks old albino Wistar rats divided into three groups namely Control, UNX and hypertensive animals. Vascular smooth muscle response was studied in isolated carotid artery of rat with acetylcholine, sodium nitroprusside, GSK1016790A (GSK) in presence and absence of L-NAME and indomethacin. Results: At the end of the 6th week, the mean systolic blood pressure was increased in DOCA-treated hypertensive rats (166 ± 8 mm Hg) compared to Control and UNX (125 ± 5 mm Hg). ACh (10–9 to 10–5 M) produced almost 100% relaxation in Control (Emax = 97.48 ± 1.06 %) and UNX animals (Emax = 93.16 ± 2.33 %) which was attenuated in DOCA-treated hypertensive animals (Emax = 70.85 ± 1.65 %). No significant changes seen in SNP (10–12 to 10–5 M) induced relaxation. GSK1016790A (10–12 to 10–7 M)-mediated relaxation was significantly attenuated in DOCA-treated hypertensive animals (Emax = 25.58 ± 13.60%) compared to the control (Emax = 80.59 ± 6.86%) and UNX (Emax = 87.32 ± 2.01%) animals. L-NAME (10–4 M) potently blocked GSK-induced relaxation, and a contractile response to GSK was observed in presence of L-NAME in all the three groups of animals which was sensitive to indomethacin (10–5 M). Conclusion: TRPV4 may regulate the vascular tone of rat carotid artery through an attenuated NO pathway and stimulation of the release of contractile prostanoids in the DOCA hypertensive rats.