The effect of extracellular calcium and preload on a teleost heart during extracellular hypercapnic acidosis

Abstract

The effect of extracellular calcium ([Ca2+]e) on the performance of the in situ perfused sea raven heart was evaluated under nonacidotic, acidotic, and high work load conditions. Increases in [Ca2+]e improved power output of the nonacidotic heart and restored control levels of power output to the heart exposed to hypercapnic acidosis (1.8% CO2, pH 7.4). Extracellular acidosis severely curtailed the scope for cardiac work (increased cardiac output and afterload), and only a 50% increase in the control, nonacidotic power output was possible with increases in preload and saturating levels of [Formula: see text]. It is suggested that increases in preload are probably more important than increases in [Ca2+]e to improve cardiac performance in the seas raven heart during extracellular acidosis.