Changes in cell-to-cell electrical coupling associated with left ventricular hypertrophy
Abstract
The impedance to current flow in the intracellular compartment of guinea pig left ventricular myocardium was measured at 20 degrees C and 37 degrees C using tissue from hypertrophied hearts subjected to aortic constriction. Alternating current of varying frequency was passed longitudinally along myocardial preparations, which revealed two time constants: one attributed to the surface membrane at the ends of the preparation and a second lying in the intracellular pathway. The longitudinal impedance was quantitatively analyzed in terms of a parallel intracellular and extracellular pathway; the former had two series components, one attributable to the sarcoplasm and the other to the low-resistance junctions between adjacent cells. This interpretation was consistent (1) with control experiments using n-heptanol, which increased the component attributed to intercellular junctions but not sarcoplasmic resistivity, and (2) with suspensions of isolated myocytes, which yielded a similar value for the sarcoplasmic resistivity. Aortic constriction increased the heart weight-to-body weight ratio of experimental animals from a mean value of 3.10 +/- 0.28 to 5.05 +/- 0.83 g/kg after 50 days of constriction and 5.60 +/- 0.95 g/kg after 150 da...Continue Reading
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