Does the ventricle limit cardiac contraction rate in the anoxic turtle (Trachemys scripta)? I. Comparison of the intrinsic contractile responses of cardiac chambers to the extracellular changes that accompany prolonged anoxia exposure.

ABSTRACT: Multiple lines of evidence suggest that an inability of the ventricle to contract in coordination with the pacemaker during anoxia exposure may suppress cardiac pumping rate in anoxia-tolerant turtles. To determine under what extracellular conditions the ventricle could be the weak link that limits cardiac pumping, we compared, under various extracellular conditions, the intrinsic contractile properties of isometrically-contracting ventricular and atrial strips obtained from 21 °C- to 5 °C- acclimated turtles (Trachemys scripta) that had been exposed to either normoxia or anoxia (16 h at 21 °C; 12 days at 5 °C). We found that combined extracellular anoxia, acidosis, and hyperkalemia (AAK), severely disrupted ventricular, but not right or left atrial, excitability and contractibility

SUBMITTER: Garner M 

PROVIDER: S-EPMC9301509 | biostudies-literature | 2022

REPOSITORIES: biostudies-literature