Sex differences in stretch-dependent effects on tension and Ca2+ transient of rat trabeculae in monocrotaline pulmonary hypertension

Abstract

We aim to compare the effects of stretch on isometric tension/Ca(2+) transient in the right ventricular trabeculae of control (CONT) and hypertensive (MCT, monocrotaline application) adult male and female rats. The treatment with MCT resulted in RV hypertrophy in males only. Blunted active force-length relation and substantially prolonged twitch were found in MCT-males but not MCT-females (vs same-sex CONT). Ca(2+) transient was prolonged in both MCT-treated groups but extremely so in the MCT-males. The gradual stretch resulted in a distinct "bump" on Ca(2+) transient decline in CONT and MCT-treated groups. The integral magnitude of the "bump" was unaffected by the treatment with MCT in males or females but was larger in males vs females. The rate of "bump" development was significantly slower in MCT-males. In conclusion, the sex-specific differences in the stretch-dependent regulation of [Ca(2+)] i may underlie preservation of the Frank-Starling mechanism in female rat myocardium in monocrotaline-induced pulmonary hypertension.

The length‐dependent activation of contraction is equally impaired in impuberal male and female rats in monocrotaline‐induced right ventricular failure

“…These findings are consistent with previous reports in which a depressed Frank–Starling mechanism and retardation of relaxation have been observed in the failing mammalian myocardium . This is commonly related to attenuation and/or prolongation of the Ca 2+ transient and to prolongation of the action potential . Depressed sarcoplasmic/endoplasmic reticulum calcium ATPase 2a activity, which has been demonstrated in the failing myocardium, may explain, at least in part, the prolongation of the decline in the Ca 2+ transient.…”

“…In rat myocardium, a brief delay in Ca 2+ transient decline (referred to as a ‘bump’) is commonly observed in isometrically contracting muscle . Consistently, an increase in muscle length results in an increase in the magnitude of the ‘bump’ but the overall decline in the Ca 2+ transient from peak to rest levels remained monotonous (Fig. a).…”

Salvia Miltiorrhiza Bge.f.alba Ameliorates the Progression of Monocrotaline-Induced Pulmonary Hypertension by Protecting Endothelial Injury in Rats

“…There were no significant changes in other indices between the low or high dose of AESM treatment, and thus an obvious dose-response relationship was not observed. Additionally, we replicated the PH model by subcutaneous injection of MCT, in which RVSP and mPAP levels were significantly higher and accompanied by a thicker pulmonary artery wall and narrower lumen after 21 days, which confirmed the success of this experimental model (Lookin et al 2015). Levels of NO (A), ET-1 (B), PGI 2 (C) and TXA 2 (D) were determined, of which PGI 2 and TXA 2 are presented with their metabolites 6-Keto-PGF 1 α and TXB 2 respectively.…”

Comparison of the effects of fetal hypothyroidism on glucose tolerance in male and female rat offspring

“…In addition, a previous study demonstrated that female rats are protected against metabolic defects typically produced by fructose feeding and detrimental effects of fructose on metabolism are less severe in this group [14]. Therefore, there is a possibility that the sexual differentiation of offspring can be affected by fetal hypothyroidism [15,16]. Since limited data are available on the relation between fetal hypothyroidism, sex differences, and carbohydrate metabolism during adult life, in this study, we hypothesized that thyroid hormone deficiency during fetal life could impair glucose tolerance in female rat offspring.…”