Loss of preconditioning in rabbits with vascular tolerance to nitroglycerin.
A preceding right ventricular overdrive pacing (VOP) of 500 b.p.m. for 5 min, markedly reduced the severity of global myocardial ischaemia produced by a subsequent 5-min VOP in conscious rabbits. This VOP-induced preconditioning developed in parallel with an increase in cardiac cyclic guanosine 3':5'-monophosphate (cyclic GMP) content. VOP-induced preconditioning was abolished when the animals had been made tolerant to the vasodilator effect of nitroglycerin (NG). In the heart of the NG-tolerant rabbits, neither VOP nor preconditioning increased cyclic GMP content. This suggests that changes by NG tolerance of cyclic GMP metabolism may account for the loss of VOP-induced preconditioning.
First Department of Medicine, Albert Szent-Györgyi University Medical School, Szeged, Hungary.
Z
Z
Szilvassy
P
P
Ferdinandy
P
P
Bor
I
I
Jakab
J
J
Szilvassy
I
I
Nagy
J
J
Lonovics
M
M
Koltai
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002304:Cardiac Pacing, Artificial; D006152:Cyclic GMP / Q000378:metabolism; D004361:Drug Tolerance; D008297:Male; D017202:Myocardial Ischemia / Q000503:physiopathology*; D005996:Nitroglycerin / Q000494:pharmacology*; D011817:Rabbits
D005996:Nitroglycerin; D006152:Cyclic GMP