Hypoxia and acidosis impair cGMP synthesis in microvascular coronary endothelial cells.
To characterize the effects of ischemia on cGMP synthesis in microvascular endothelium, cultured endothelial cells from adult rat hearts were exposed to hypoxia or normoxia at pH 6.4 or 7.4. Cellular cGMP and soluble (sGC) and membrane guanylyl cyclase (mGC) activities were measured after stimulation of sGC (S-nitroso-N-acetyl-penicillamine) or mGC (urodilatin) or after no stimulation. Cell death (lactate dehydrogenase release) was negligible in all experiments. Hypoxia at pH 6.4 induced a rapid approximately 90% decrease in cellular cGMP after sGC and mGC stimulation. This effect was reproduced by acidosis. Hypoxia at pH 7.4 elicited a less pronounced (approximately 50%) and slower reduction in cGMP synthesis. Reoxygenation after 2 h of hypoxia at either pH 6.4 or 7.4 normalized the response to mGC stimulation but further deteriorated the sGC response; normalization of pH rapidly reversed the effects of acidosis. At pH 7.4, the response to GC stimulation correlated well with cellular ATP. We conclude that simulated ischemia severely depresses cGMP synthesis in microvascular coronary endothelial cells through ATP depletion and acidosis without intrinsic protein alteration.
Servicio de Cardiología, Hospital Universitari Vall d'Hebron, 08035 Barcelona, Spain.
Luis
L
Agulló
David
D
Garcia-Dorado
Noelia
N
Escalona
Javier
J
Inserte
Marisol
M
Ruiz-Meana
José A
JA
Barrabés
Maribel
M
Mirabet
Pilar
P
Pina
Jordi
J
Soler-Soler
D000138:Acidosis / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D009320:Atrial Natriuretic Factor / Q000378:metabolism; D003331:Coronary Vessels / Q000378:metabolism*; D006152:Cyclic GMP / Q000096:biosynthesis*; D004730:Endothelium, Vascular / Q000166:cytology / Q000201:enzymology*; D004734:Energy Metabolism / Q000502:physiology; D004789:Enzyme Activation / Q000502:physiology; D006162:Guanylate Cyclase / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D000860:Hypoxia / Q000378:metabolism*; D008297:Male; D008833:Microcirculation / Q000502:physiology; D009569:Nitric Oxide / Q000378:metabolism; D018384:Oxidative Stress / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D015427:Reperfusion Injury / Q000378:metabolism
D009569:Nitric Oxide; D009320:Atrial Natriuretic Factor; D000255:Adenosine Triphosphate; D006162:Guanylate Cyclase; D006152:Cyclic GMP