Direct measurements of SR free Ca reveal the mechanism underlying the transient effects of RyR potentiation under physiological conditions.

ABSTRACT:

Aims

Most of the calcium that activates contraction is released from the sarcoplasmic reticulum (SR) through the ryanodine receptor (RyR). It is controversial whether activators of the RyR produce a maintained increase in the amplitude of the systolic Ca transient. We therefore aimed to examine the effects of activation of the RyR in large animals under conditions designed to be as physiological as possible while simultaneously measuring SR and cytoplasmic Ca.

Methods and results

Experiments were performed on ventricular myocytes from canine and ovine hearts. Cytoplasmic Ca was measured with fluo-3 and SR Ca with mag-fura-2. Application of caffeine resulted in a brief increase in the amplitude of the systolic Ca transient accompanied by an increase of action potential durati

SUBMITTER: Greensmith DJ 

PROVIDER: S-EPMC4145011 | biostudies-literature | 2014 Sep

REPOSITORIES: biostudies-literature