Contraction of atrial and ventricular myocardium after treatment with ethylenediaminetetraacetic acid and glycerol.
Treatment of fiber bundles of EDTA produced high sarcolemmal permeability and eliminated the necessity of electrical stimulation of both strips of left atria (A) or left ventricular papillary muscles (P) in order to achieve activation. Subsequent Ca++-stimulated contractures developed peak tension in less time and with higher velocity in A than in P. Long term glycerination of fiber bundles, prepared from both A and P, disrupted subcellular membranes in addition to disruption of sarcolema. The bundles were then activated by addition of Ca++ and ATP, and the time course of contracture development was recorded. No difference was observed in the rate of contracture tension development from the onset to the peak tension developed between A and P. These results indicate that the major determinants of the differences in velocity and time course of tension development between atria and ventricles may reside in the coupling and uncoupling processes, rather than in sarcolemma or in the contractile proteins.
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D016275:Atrial Function; D004492:Edetic Acid / Q000494:pharmacology*; D005990:Glycerol / Q000494:pharmacology*; D006325:Heart Atria / Q000187:drug effects; D008297:Male; D008566:Membranes / Q000187:drug effects; D009200:Myocardial Contraction / Q000187:drug effects*; D010210:Papillary Muscles / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D012508:Sarcolemma / Q000187:drug effects; D013997:Time Factors
D004492:Edetic Acid; D005990:Glycerol