Attenuated Ca2+ response to acetylcholine in endothelial cells from aorta of aldosterone-salt hypertensive rats.
Ca2+ is essential for endothelial production of vasorelaxing factors. We determined whether the impaired endothelium-dependent relaxation in aldosterone-salt hypertensive rats (AHR) is associated with a decreased free Ca2+ ([Ca2+]i) response in endothelial cells. In isolated aorta, the EC50 for the acetylcholine-induced endothelium-dependent relaxations did not differ between AHR and the age-matched control-salt rats (CSR). However, maximal relaxation was significantly reduced by 47% in AHR (P < .05). In contrast, the endothelium-independent relaxation to sodium nitroprusside was not impaired in aorta from AHR. The [Ca2+]i was measured with fura-2 microfluorometry in endothelial cells freshly dispersed from aorta. Although the basal [Ca2+]i was not different between CSR and AHR, the peak [Ca2+]i response to acetylcholine was significantly reduced in cells from AHR compared with CSR (P < .05). These results suggest that depressed endothelial [Ca2+]i responses to acetylcholine may be involved in the impaired endothelium-dependent relaxation in aorta from AHR.
Liu
Y
Y
Vascular Cell Biophysics Laboratory, Dalton Cardiovascular Research Center, Columbia, MO 65211, USA.
Jones
A W
AW
Sturek
M
M
D000109:Acetylcholine / Q000494:pharmacology*; D000450:Aldosterone; D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology*; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects*; D016257:Fura-2; D006973:Hypertension / Q000139:chemically induced / Q000503:physiopathology*; D066298:In Vitro Techniques; D007213:Indomethacin / Q000494:pharmacology; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009126:Muscle Relaxation / Q000187:drug effects; D019331:NG-Nitroarginine Methyl Ester; D009569:Nitric Oxide / Q000037:antagonists & inhibitors; D009599:Nitroprusside / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012965:Sodium Chloride
D009599:Nitroprusside; D009569:Nitric Oxide; D012965:Sodium Chloride; D000450:Aldosterone; D001120:Arginine; D000109:Acetylcholine; D002118:Calcium; D016257:Fura-2; D019331:NG-Nitroarginine Methyl Ester; D007213:Indomethacin