Hydroxyproline in all parts of the rabbit heart in hypertension and in its reversal.

To investigate the response of cardiac collagen to arterial hypertension and its reversal, we measured the hydroxyproline concentration in all parts of the rabbit heart in three groups: a chronic hypertension group (n = 11), a reversal group (n = 9) and an age-matched control group (n = 10). Left ventricular overload was produced by one-kidney, one-clip Goldblatt hypertension and its reversal was produced by clip release. The wet weight of every part of the left side of the heart was increased by hypertension and all parts except for the papillary muscles showed regression with reversal. However, the response of collagen was quite different among the various parts of the heart. The wet weights of the left atrium, left ventricular free wall, interventricular septum, and anterior and posterior papillary muscle in the hypertension group were 144 (P less than 0.01), 140 (P less than 0.01), 134 (P less than 0.01), 144 (P less than 0.01) and 129% (P less than 0.01), respectively, and those in the reversal group were 92, 113 (P less than 0.05), 107 (P less than 0.05), 142 (P less than 0.05) and 126% (P less than 0.05) of those in the control group, respectively. Hydroxyproline concentrations in the respective parts in the hypertension group were 79 (P less than 0.05), 91, 98, 121 (P less than 0.05) and 120% (P less than 0.05) and those in the reversal group were 86, 93, 94, 107 and 110% of those in the control group.(ABSTRACT TRUNCATED AT 250 WORDS)