Metabolic and mechanical properties of aortas from aldosterone-salt hypertensive rats.

Aortas from aldosterone-salt treated hypertensive rats and vehicle-infused normotensive controls were compared with respect to mechanical properties, metabolism, and energy turnover. Passive wall stress at any given circumference was slightly higher in aortas from the hypertensive rats, whereas active isometric force normalized to cross-sectional area was similar in vessels from the two groups at their respective optimal circumference for active tension developments [hypertensive rats: (n = 14), 19.73 +/- 1.98; controls: (n = 13), 22.57 +/- 2.13 mN/mm2). Metabolic parameters were measured with the aortas held at optimal circumference for active tension development, the optimal length for tension development (n = 6), 5.67 +/- 0.17 and (n = 7), 5.29 +/- 0.18 mm for control and aldosterone-salt groups, respectively. Basal oxygen consumption rate was elevated significantly in aortas from the hypertensive rats [(n = 14), 0.457 +/- 0.026 vs. (n = 13), 0.267 +/- 0.028 mumol/min per g; P less than 0.001]. Under resting conditions, lactate production rate similar in aortas from the two groups [hypertensive rats: (n = 20), 0.129 +/- 0.010; controls: (n = 21), 0.112 +/- 0.008 mumol/min per g]. Upon activation with added KCl, the rate of oxygen consumption and lactate production increased with tension development in both groups, but the stimulated rate of oxygen consumption was higher in hypertensives compared to controls [(n = 14), 0.580 +/- 0.031 vs. (n = 13), 0.441 +/- 0.049 mumol/min per g; P less than 0.025]. The stimulated rates of lactate production were similar in the two groups [hypertensive rats: (n = 20), 0.172 +/- 0.009; controls: (n = 21), 0.118 +/- 0.009].(ABSTRACT TRUNCATED AT 250 WORDS)