Role of K+, Na+, and Ca2+ ions in the cardiodepressive action of blood plasma in burn shock and the crush syndrome

Ion-selective electrodes were employed to measure the concentration of K+, Na+ and Ca2+ in blood plasma of rabbits with burn shock or crush syndrome (CS). No significant changes in the plasma concentration of Na+, and Ca2+ were found under both pathological conditions. The plasma concentration of K+ in burn shock significantly increased from 3.06 +/- 0.73 (control) to 5.28 +/- 2.65 mM (n = 10), whereas in CS from 3.42 +/- 1.03 to 4.92 +/- 1,29 mM (n = 8). The rise of K+ concentration in the control plasma to the maximal values seen in the "burn" and "syndrome" plasma led to an increase in the duration of intracellular action potentials (AP) but did not substantially change the amplitude of isometric contractions of the papillary muscles of rabbit heart. Meanwhile the similar rise of the duration of intracellular AP during perfusion of the papillary muscles with the "burn" and "syndrome" plasma was accompanied by an appreciable drop of the amplitude of isometric contractions. It is suggested that elevation of K+ concentration in blood plasma, inducing an increase in the duration of intracellular AP of cardiocytes may be responsible for changes in the ECG in burn and CS. At the same time inhibition of myocardial contractility in burn shock and CS is virtually not linked with hyperkalemia.