title: Pathophysiological mechanisms of altered transmembrane potentials in diseased human atria.
abstract: The pathophysiological mechanisms of altered transmembrane potentials in diseased human atria were investigated in 20 patients who were divided into group A (normal) and group B (diseased). The electrophysiological data of right atrial tissues measured with glass microelectrodes included maximum diastolic potentials (MDP), action potential amplitudes (APA) and action potential durations at the time required for 50% repolarization (ADP 50%) and 75% repolarization (APD 75%). The sarcolemma isolated from atrial tissues was used for determination of the sarcolemmal Na+-K+ ATPase activities. Anionic molecular sites distributed in the sarcolemmal complex were characterized by cationized ferritins (CF). The electrophysiological data in groups A and B were: MDP -80.74 +/- 1.94 mV and -44.54 +/- 6.24 mV, APA 92.72 +/- 9.25 mV and 57.74 +/- 10.85 mV, APD 50% 42.48 +/- 6.63 msec and 210.34 +/- 36.38 msec and APD 75% 56.47 +/- 8.55 msec and 281.66 +/- 42.18 msec respectively. The difference in the Na+-K+ ATPase activities between groups A (15.37 +/- 0.46 mumole Pi/mg/hr) and B (12.55 +/- 0.4 mumole Pi/mg/hr) was highly significant. CF molecules were frequently seen to be more irregularly and loosely distributed in the sarcolemmal surfaces of group B atrial myocytes. Based on these results we conclude that depression of the sarcolemmal Na+-K+ ATPase activity and derangement of the anionic binding sites in the sarcolemmal surfaces play an important role in altering transmembrane potentials in diseased human atria.
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D003971:Diastole; D004594:Electrophysiology; D005260:Female; D005293:Ferritins / Q000378:metabolism; D006325:Heart Atria / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D006331:Heart Diseases / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D006651:Histocytochemistry; D006801:Humans; D008297:Male; D008564:Membrane Potentials; D012508:Sarcolemma / Q000201:enzymology / Q000648:ultrastructure; D000254:Sodium-Potassium-Exchanging ATPase / Q000032:analysis
chemical_list: D005293:Ferritins; D000254:Sodium-Potassium-Exchanging ATPase