The influence of KCl concentration on the contraction kinetics of skinned frog muscle fibers at 5-7 degrees C was studied at various calcium levels. The magnitude of the calcium-activated force decreased continuously as the KCl concentration of the bathing solution was increased from 0 to 280 mM. The shortening velocity at a given relative load was unaffected by the level of calcium activation ...

1. Papaverine, in the concentration range 50-150 microM, inhibited rhythmic spontaneous contraction and caused relaxation of KCl-induced contractures of rat ileal smooth muscle. 2. Spontaneous slow waves and spikes declined at low papaverine concentrations. 3. The normal 45Ca uptake of the ileum was reduced by papaverin. Although papaverine caused only a small inhibition of normal 45Ca efflux f...

Isoflavones decrease blood pressure, improve lipid profiles, and restore vascular function. We hypothesized that isoflavone attenuates vascular contraction by inhibiting RhoA/Rho-kinase signaling pathway. Rat aortic rings were denuded of endothelium, mounted in organ baths, and contracted with 11,9 epoxymethano-prostaglandin F(2alpha) (U46619), a thromboxane A2 analog, or KCl 30 min after the p...

Background & Aims: Considering the higher incidence of cardiovascular disorders in diabetes mellitus and some evidence on antioxidant and antidiabetic potential of Tribulus terrestris (TT), this study was conducted to evaluate the beneficial effect of 6-week oral administration of TT on contractile reactivity of isolated thoracic aorta in diabetic rats. Methods: Female Wistar rats were divided ...

Neonatal ventricular myocytes that were incubated in a well-defined serum-free medium containing 50 mM KCl did not contract and maintained stable cell size, as assessed by the protein/DNA ratio. The present study utilized KCl-arrested cells to examine the effect of constant rates of synchronous contraction in normal [K+]o (4 mM) as a physiological stimulus for myocyte growth. Cell growth increa...

We previously identified glucose-6-phosphate dehydrogenase (G6PD) as a regulator of vascular smooth muscle contraction. In this study, we tested our hypothesis that G6PD activated by KCl via a phosphatase and tensin homologue deleted on chromosome 10 (PTEN)-protein kinase C (PKC) pathway increases vascular smooth muscle contraction and that inhibition of G6PD relaxes smooth muscle by decreasing...

Background & Aims: Considering increasing incidence of cardiovascular disorders in diabetes mellitus and some evidence on antioxidant and antidiabetic potentials of naringenin, this study was conducted to evaluate the beneficial effects of 6-week administration of naringenin on contractile reactivity of isolated thoracic aorta in diabetic rats. Methods: Male Wistar rats were divided into contro...

Objective(s): Thyroid hormones play an essential role in fetal growth and maternal hypo-thyroidism which leads to cardiovascular deficiency in their offspring.  Considering this, we intended to investigate the impact of gestational hypothyroidism on offspring vascular contractibility and possible underlying mechanisms. Materials and Methods: Hypothyroidism was induced in female rats by administ...

The inotropic actions of isoproterenol in cat papillary muscles or trabeculae bathed in a salt solution containing 4 mM KCl were compared to those in similar muscles bathed in a salt solution containing 22 mM KC1. Although isoproterenol evoked the same increase in force of contraction in both groups of muscles, the time course of contraction differed markedly. In muscles bathed in 4 mM KC1, iso...

objective(s): thyroid hormones play an essential role in fetal growth and maternal hypo-thyroidism which leads to cardiovascular deficiency in their offspring.  considering this, we intended to investigate the impact of gestational hypothyroidism on offspring vascular contractibility and possible underlying mechanisms. materials and methods: hypothyroidism was induced in female rats by administ...