Effect of substrates on the mechanical performance of rhesus monkey papillary muscle.

This study examines the effect of different substrates on mechanical performance of excised papillary muscles from rhesus monkeys which had been divided into a control group and an experimental group fed a high fat diet for 5 months prior to sacrifice. The results show that performance is affected by availabel substrate for both groups. The performance of the experimental group was depressed relative to control with the short chain fatty acid, butyrate (C4), producing a monotonically decreasing force-frequency response. Relative to the other mammals, isolated rhesus papillary muscles exhibited a protracted treppe which was sensitive to beta-adrenergic blockade with propranolol.