Rats are Protected from the Stress of Chronic Pressure Overload as Compared with Mice.

Rats are Protected from the Stress of Chronic Pressure Overload as Compared with Mice.
Am J Physiol Regul Integr Comp Physiol. 2020 Mar 25;:
Authors: Nishimura K, Oydanich M, Zhang J, Babici D, Fraidenraich D, Vatner DE, Vatner SF
Abstract
The goal of this investigation was to compare the effects of chronic (4 weeks) transverse aortic constriction (TAC) in Sprague Dawley rats and C57BL/6J mice. TAC, after 1 day, induced similar left ventricular (LV) pressure gradients in both rats (n=7) and mice (n=7) (113 ± 5.4 vs. 103 ± 11.5 mmHg) and after 4 weeks, the % increase in LV hypertrophy, as reflected by LV/tibial length (51% vs 49%) were similar in rats (n=12) and mice (n=12). After 4 weeks of TAC LV systolic and diastolic function were preserved in TAC rats. In contrast, in TAC mice LV ejection fraction decreased by 31% compared to sham, along with increases in LV end diastolic pressure (153%), and LV systolic wall stress (86%). Angiogenesis, as reflected by Ki67 staining of capillaries, increased more in rats (n=6) than mice (n=6) (10 ± 2 vs. 6 ± 1 Ki67 positive cells/field). Myocardial blood flow fell by 55% and coronary reserve fell by 28% in mice with TAC (n=4), but were preserved in rats (n=4). Myogenesis, as reflected by c-kit positive myocytes staining positively for Troponin I, is another mechanism that can confer protection after TAC. However, the c-kit positive cells in rats with TAC were all negative for Troponin I, indi...

Source: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology - March 24, 2020 Category: Physiology Authors: Nishimura K, Oydanich M, Zhang J, Babici D, Fraidenraich D, Vatner DE, Vatner SF Tags: Am J Physiol Regul Integr Comp Physiol Source Type: research