Developmental changes in regulation of mitochondrial respiration by ADP and creatine in rat heart in vivo.

In saponin-skinned muscle fibers from adult rat heart and m. soleus the apparent affinity of the mitochondrial oxidative phosphorylation system for ADP (Km = 200-400 microM) is much lower than in isolated mitochondria (Km = 10-20 microM). This suggests a limited permeability of the outer mitochondrial membrane (OMM) to adenine nucleotides in slow-twitch muscle cells.

Thyroid control over membrane processes in rat heart.

We have studied the effects of hypo- and hyperthyroidism on sarcolemmal (SL) and sarcoplasmic reticular (SR) ion transport processes and mitochondrial energy production in rat heart. The following conclusions were derived. 1) Compared with euthyroid state, hyperthyroidism led to increased SR Ca(2+)-accumulation.