AJP - Heart and Circulatory Physiology, Vol 266, Issue 5 1886-H1895, Copyright © 1994 by American Physiological Society

ARTICLES

Characteristics of myocytes isolated from hearts of renovascular hypertensive guinea pigs

R. U. Naqvi, F. del Monte, P. O'Gara, S. E. Harding and K. T. MacLeod
Department of Cardiac Medicine, National Heart and Lung Institute, London, United Kingdom.

A model of renovascular hypertension has been developed in the guinea pig using the Goldblatt (2-kidney, 1-clip) operation. Systolic and diastolic blood pressures were significantly increased 3 and 7 wk after the operation, but levels fell to control values at 11 wk. The two-dimensional areas of myocytes isolated from the hearts of Goldblatt-operated (GB) animals were larger than those in control cells at 3 wk (cf. 3,397 +/- 87 and 2,208 +/- 125 microns 2, P < 0.01), and the difference was maintained at 7 and 11 wk. No change in cell contraction or relaxation characteristics were seen at either 3 or 7 wk after clipping. Myocytes from the 11-wk GB group showed a significantly reduced contraction amplitude and velocity at 32 degrees C in maximally activating Ca2+ or isoproterenol concentrations (%cell shortening in Ca2+, cf. 6.8 +/- 0.4 and 10.0 +/- 0.9, P < 0.01). Concentrations eliciting 50% of maximal response for Ca2+ or isoproterenol were unchanged, as was the ratio of isoproterenol to Ca2+ effect in the same cell. Increases in time to peak contraction (TTP) and time to 50% relaxation (R50) were observed in 11-wk GB myocytes, but only at room temperature. There was no lengthening of TTP or R50 of the Ca2+ transient, nor was there any change in Ca2+ current density or inactivation kinetics in these myocytes.

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				C. M. N. Terracciano, R. U. Naqvi, and K. T. MacLeod Effects of Rest Interval on the Release of Calcium From the Sarcoplasmic Reticulum in Isolated Guinea Pig Ventricular Myocytes Circ. Res., August 1, 1995; 77(2): 354 - 360. [Abstract] [Full Text]