Effect of ischemia on soluble and particulate guanylyl cyclase-mediated cGMP synthesis in cardiomyocytes.
The effect of simulated ischemia [hypoxia, no glucose, extracellular pH (pH(o)) 6.4] on cGMP synthesis induced by stimulation of soluble (sGC) or particulate guanylyl cyclase (pGC) was investigated in adult rat cardiomyocytes. Intracellular cGMP content was measured after stimulation of sGC by S-nitroso-N-penicillamine (SNAP) or stimulation of pGC by natriuretic peptides [urodilatin (Uro), atrial natriuretic peptide (ANP), or C-type natriuretic peptide (CNP)] for 1 min in the presence of phosphodiesterase inhibitors. After 2 h of simulated ischemia, a decrease of >50% was observed in pGC-dependent cGMP synthesis, but no significant change was observed in sGC-dependent cGMP synthesis. The reduction in cGMP synthesis caused by simulated ischemia was mimicked by extracellular acidosis (pH(o) 6.4), which decreased pGC-mediated cGMP synthesis without altering sGC-mediated cGMP synthesis. An extreme sensitivity of pGC activity to low pH was also observed in membrane cell fractions. Hypoxia without acidosis (pH(o) 7.4) profoundly depressed cellular ATP content but did not change the response to SNAP, Uro, or ANP (selective agonists of pGC type A receptor). Only cGMP synthesis in response to CNP (a selective agonist of pGC type B receptor) was significantly reduced by ATP depletion. These data support the relevance of intracellular pH as a modulator of cGMP and suggest that, in ischemic cardiomyocytes, synthesis of cGMP would be mainly nitric oxide dependent.
Agulló
Luis
L
Servicio de Cardiologia, Hospital Universitari Vall d'Hebron, 08035 Barcelona, Spain.
Garcia-Dorado
David
D
Escalona
Noelia
N
Ruiz-Meana
Marisol
M
Inserte
Javier
J
Soler-Soler
Jordi
J
D000138:Acidosis / Q000503:physiopathology; D000255:Adenosine Triphosphate / Q000378:metabolism / Q000502:physiology; D000818:Animals; D009320:Atrial Natriuretic Factor / Q000494:pharmacology; D001993:Bronchodilator Agents / Q000494:pharmacology; D002462:Cell Membrane / Q000201:enzymology; D006152:Cyclic GMP / Q000096:biosynthesis*; D006162:Guanylate Cyclase / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008297:Male; D032342:Muscle Cells / Q000201:enzymology*; D015428:Myocardial Reperfusion Injury / Q000201:enzymology*; D009206:Myocardium / Q000166:cytology / Q000201:enzymology*; D020098:Natriuretic Peptide, C-Type / Q000494:pharmacology; D020030:Nitric Oxide Donors / Q000494:pharmacology; D010446:Peptide Fragments / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D026423:S-Nitroso-N-Acetylpenicillamine / Q000494:pharmacology; D012995:Solubility
D001993:Bronchodilator Agents; D020030:Nitric Oxide Donors; D010446:Peptide Fragments; D020098:Natriuretic Peptide, C-Type; C056452:Ularitide; D026423:S-Nitroso-N-Acetylpenicillamine; D009320:Atrial Natriuretic Factor; D000255:Adenosine Triphosphate; D007770:L-Lactate Dehydrogenase; D006162:Guanylate Cyclase; D006152:Cyclic GMP