Comparative study of isoproterenol and 4-deoxypyridoxine effects on the isovolumic rat heart model

Isovolumic rat hearts were perfused for 20 min (T20) or 40 min (T40) with 10(-6) M isoproterenol (ISO), 10(-5) M 4-Deoxypiridoxine (DOP) or with both drugs (ISO-DOP). ISO increased developed pressure 51% and 31%, coronary flow (C.F.) 37% and 52%, heart rate 50% and 60%, lactate production 160% and 76%, and CK activity in the effluent perfusate 182% and 173% at T20 and T40 respectively, whereas glycogen stores decreased by 47% and 77%. DOP needed at least 40 min to increase heart rate 32%, C.F. 40% and to decrease glycogen reserves by 33% and pyridoxal-5-phosphate 13%. In the ISO-DOP group, the ISO inotropic effect was lowered by 23% (T20) and 25% (T40) and DOP reduced ISO induced glycogenolysis.