Coronary blood flow in genetic cardiac hypertrophy

6he effects of cardiac hypertrophy on coronary circulation was evaluated in 4 related strains of rats: the M520/N strain (n = 7), which has genetic cardiac hypertrophy but a normal blood pressure; the LA/N strain (n = 8), which has a somewhat small heart with normal blood pressure; the SHRSP/N strain (n = 8), which is hypertensive with marked left ventricular (LV) hypertrophy; and the WKY/N strain (n = 7), from which the SHR-Sp was developed. At 11 to 12 weeks of age, systemic and coronary hemodynamics were studied by 15-mu radioactive microspheres injected through the left atrium in conscious, unrestrained rats. Coronary blood flow was determined both at rest and after maximal vasodilation by carbochrome (6 mg/kg). LV weight was significantly higher in both the SHRSP/N (3.19 +/- 0.10 mg/g [+/- standard error], p less than 0.01) and the M520/N (2.82 +/- 0.08 mg/g, p less than 0.01) strains than in the WKY/N strain (2.30 +/- 0.08 mg/g); it was significantly smaller in the LA/N strain (1.96 +/- 0.04 mg/g, p less than 0.01). Coronary flow at rest was similar among the 4 groups; however, carbochrome-induced "maximal" flow differed among the groups. It was almost equal among the SHRSP/N (1,176 +/- 151 ml/m/100 g), the LA/N (1,356 +/- 149 ml/m/100 g) and the WKY/N strains (1,263 +/- 143 ml/m/100 g), but it was markedly decreased in the M520/N strain compared with the 3 other groups (632 +/- 83 ml/m/100 g, p less than 0.05 vs WKY/N and p less than 0.01 vs SHRSP/N and LA/N).(ABSTRACT TRUNCATED AT 250 WORDS)