Dopamine receptors in the hypertrophied rat heart

1. Dopamine (DA) binding sites in the left and right ventricle of hypertensive rats were assessed after two weeks of induction of hypertension by left renal artery occlusion. 2. The ratio of left ventricular (LV) weight to total body weight was significantly increased in hypertensive rats from 2.046 +/- 0.120 mg g-1 to 3.125 +/- 0.090 mg g-1 (P less than 0.01) while no significant difference was noted in the right ventricle (RV). 3. The hypertrophied LV was associated with a 78% increase in its protein content, however, the ratio of protein content to ventricular wet weight was not significantly different from controls. No change in RV protein content and concentration was observed. 4. Dopamine affinity of sarcolemmal protein was not significantly different in control and experimental LV and RV and the ratio of DA affinity in LV:RV was 10:1. 5. Saturation of LV with DA was reached at around 7 min whereas RV was saturated at approximately 15 min.