Activation of the adrenergic receptor ( AR) induces a tightly controlled cAMP/protein kinase A (PKA) activity to ensure an agonist dose-dependent and saturable contraction response in animal heart. We have found that stimulation of 1AR by isoproterenol induces maximal contraction responses at the dose of 1 M in cardiac myocytes; however, cAMP accumulation continues to increase with higher agoni...

In hypertension, blood vessels exhibit increased reactive oxygen species production that may alter vascular tone. We previously observed that H2O2 contracted rat thoracic vena cava under resting tone and aorta contracted with KCl. In arteries but not veins, H2O2-induced contraction required extracellular Ca2+ influx. Because of this difference in Ca2+ utilization, we hypothesized that signaling...

background: accidents are the second reason for mortality and morbidity in iran. among them, brain injuries are the most important damage. clarification of the effects of brain injuries on different body systems will help physicians to prioritize their treatment strategies. in this study, the effect of pure brain trauma on the cardiovascular system and lungs 24 hours post trauma was assessed. m...

Let T be a periodic time scale. The purpose of this paper is to use a modification of Krasnoselskii’s fixed point theorem due to T. A. Burton to show that the totally nonlinear dynamic equation with functional delay x△(t) =−a(t)x3(σ(t))+G ( t, x3(t), x3(t − r(t)) ) , t ∈ T, has a periodic solution. We invert this equation to construct a sum of a compact map and a large contraction, which is sui...

We study the existence of periodic solutions of the second order nonlinear neutral differential equation with variable delay x′′ (t) + p (t)x′ (t) + q (t)h (x (t)) = c (t)x′ (t− τ (t)) + f (t, x (t− τ (t))) . We invert the given equation to obtain an integral, but equivalent, equation from which we define a fixed point mapping written as a sum of a large contraction and a compact map. We show t...

Fas ligand (FasL) and perforin pathways not only are the major mechanisms of T cell-mediated cytotoxicity but also are involved in homeostatic regulation of these T cells. In the present study, we tested whether CD8+ donor T cells that are deficient in both perforin and FasL (cytotoxic double deficient [cdd]) could induce graft-versus-host disease (GVHD) in a major histocompatibility complex cl...

To characterize the pump function of the left atrium, we determined the instantaneous pressure-volume relation of the isolated supported left atrium. A physiologic after-loading system for the low-pressure atrium was created by coupling it to a real-time computer-simulated ventricle and a simulated venous impedance network via a volume servo-pump. In 10 atria loaded with such systems, multiple ...

background: there is much debate about effects of medicinal plants such as saffron (crocus sativus) on human health. women are highly involved in farming and processing of this plant. this study is aimed at evaluating the saffron impacts on miscarriage rate of female farmers working in saffron fields. methods: this was a prospective case-control study on pregnant female farmers during harvestin...

A B S T R A C T Cultured, spontaneously beating heart cells were used to study the role of calmodulin in regulating cardiac contraction. Trifluoperazine (TFP), an antipsychotic drug that binds to calmodulin, reversibly inhibited myocardial contraction. This effect occurred over a TFP concentration range of 5-100 MM with half maximal activity at -15 uM TFP. When the phosphoprotein profile of TFP...

The mechanism of excitation-contraction (E-C) coupling in skeletal muscle is not yet well established. Cultured mouse skeletal muscle cells have been used to study the relationships between triad formation, Ca2+ channel activities, and contractions. The ontogenesis of voltage-dependent Ca2+ channels and their localization in relation to the ability of muscle to contract and the ultrastructural ...