Contractile responses to electrolyte changes during coronary bolus perfusion. A comparative study in isolated rat, guinea pig, and rabbit hearts.
OBJECTIVE
The authors studied cardiac contractile responses during coronary bolus perfusion, as in coronary angiography, in three species and related the responses to the bolus content of electrolytes and to patterns of cardiac electrolyte regulation.


METHODS
Isolated, paced hearts from the rat, guinea pig, and rabbit were subjected to coronary perfusion in the global mode with recording of left ventricular developed pressure during exposure (< 7.5 seconds) and recovery (30 seconds).


RESULTS
In series 1 of the experiments, the perfusate reduction to one fifth of normal Ca, Na, K, Mg, and Ca/Na/K/Mg, and the removal of all ions, led to the following percentage changes in left ventricular developed pressure: rat -64, +84, -38, +7, +40, and +79; guinea pig -43, +48, +18, +5, +28, and +37; and rabbit -32, +60, +14, +4, +22, and +33.


CONCLUSIONS
Except for K reduction, inducing negative inotropy in the rat but positive inotropy in the guinea pig and the rabbit, the three species responded similarly. Thus, changes in left ventricular developed pressure were related to changes in direction and rate of the sarcomal Na-Ca exchange. In series 2 of the experiments, iohexol (150 mg I/mL) +/- minor electrolyte additives were studied. Additives with Na 30 mmol/L only or with Na, Ca, K, and Mg carefully balanced reduced positive and negative inotropic responses in all three species.
Jynge
P
P
Department of Pharmacology and Toxicology, Faculty of Medicine, University of Trondheim, Norway.
Blankson
H
H
Schjøtt
J
J
Holten
T
T
Oksendal
A N
AN
D000704:Analysis of Variance; D000818:Animals; D003331:Coronary Vessels; D004558:Electric Stimulation; D004573:Electrolytes / Q000008:administration & dosage / Q000494:pharmacology*; D006168:Guinea Pigs; D007472:Iohexol / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects* / Q000502:physiology; D010477:Perfusion / Q000379:methods; D011817:Rabbits; D051381:Rats; D017208:Rats, Wistar; D013045:Species Specificity; D013997:Time Factors
D004573:Electrolytes; D007472:Iohexol