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

Abstract

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)

Metabolic characteristics of aorta from spontaneously hypertensive and renal and deoxycorticosterone acetate-salt hypertensive rats.

“…These changes in lactate production during stimulation are different from those observed by others. McMahon and Paul 4 reported an increase in lactate production with KCI stimulation in aortas from both control and aldosterone-salt hypertensive rats, but Amer and Hellstrand 3 reported a decrease during stimulation of aortas from both control and SHR. Although the reasons for these observational discrepancies are All values are means + SEM; the number of observations is in parentheses.…”

“…Similar conclusions were reached by Arner and Hellstrand 3 and McMahon and Paul. 4 The reason for the higher basal oxygen consumption in aortas from hypertensive rats is unknown. Since only basal oxygen consumption was elevated in all hypertensive models, it cannot be explained by an elevation in the proportion of muscle cells.…”

“…When com-pared with aortas from normotensive rats, aortas from both models exhibited an elevated basal rate of oxygen consumption, which confirms the earlier work of Daly 2 and Gambetta-Gurpide 1 ; however, the elevation was much greater in the aldosterone-salt model. 4 During tension development in response to elevated extracellular K + , oxygen consumption increased relative to basal values in both models; however, only in aortas from aldosterone-salt treated rats was the rate of consumption during stimulation greater than that of the normotensive control. 4 Lactate production was observed to decrease during tension development in aortas from SHR 3 and to increase in aortas from aldosterone-salt-treated rats.…”

“…4 During tension development in response to elevated extracellular K + , oxygen consumption increased relative to basal values in both models; however, only in aortas from aldosterone-salt treated rats was the rate of consumption during stimulation greater than that of the normotensive control. 4 Lactate production was observed to decrease during tension development in aortas from SHR 3 and to increase in aortas from aldosterone-salt-treated rats. 4 Because of potential methodological differences between these two studies, it is not clear if the observed differences in the metabolic characteristics of vessels from these two forms of hypertension reflect differences in tissue response to these two models of hypertension.…”

“…4 Lactate production was observed to decrease during tension development in aortas from SHR 3 and to increase in aortas from aldosterone-salt-treated rats. 4 Because of potential methodological differences between these two studies, it is not clear if the observed differences in the metabolic characteristics of vessels from these two forms of hypertension reflect differences in tissue response to these two models of hypertension.…”