Electrical excitability of roach ( Rutilus rutilus) ventricular myocytes: effects of extracellular K, temperature, and pacing frequency.

Exercise, capture, and handling stress in fish can elevate extracellular K concentration ([K]) with potential impact on heart function in a temperature- and frequency-dependent manner. To this end, the effects of [K] on the excitability of ventricular myocytes of winter-acclimatized roach ( Rutilus rutilus) (4 ± 0.5°C) were examined at different test temperatures and varying pacing rates.

Effects of seasonal acclimatization on thermal tolerance of inward currents in roach (Rutilus rutilus) cardiac myocytes.

To test the hypothesis of temperature-dependent deterioration of electrical excitability (TDEE) (Vornanen, J Exp Biol 219:1941-1952, 2016), the role of sodium (I ) and calcium (I ) currents in heat tolerance of cardiac excitability was examined in a eurythermic fish, the roach (Rutilus rutilus). Densities of cardiac I and I and their acute heat tolerance were measured in winter-acclimatized (WiR) and summer-acclimatized (SuR) fish maintained in the laboratory at 4 ± 1 and 18 ± 1 °C, respectively. A robust L-type Ca current (I ), but no T-type Ca current, was present in roach atrial and ventricular myocytes.