Large-conductance Ca(2+)-activated potassium (BK) channels modulate vascular tone. Tempol, an O(2)(-) dismutase mimetic, causes vasodilation via activation of vascular BK channels. In this study, we investigated the mechanisms underlying tempol-induced activation of BK channels in mesenteric arterial (MA) myocytes from sham and deoxycorticosterone acetate (DOCA)-salt hypertensive rats. In sham ...

Objective: Catecholamines that accompany acute physiological stress are also involved in mediating the development of hypertrophy and failure. However, the cellular mechanisms involved in catecholamine-induced cardiac hypertrophy, particularly Ca + handling, are largely unknown. We therefore investigated the effects of cardiac hypertrophy, produced by isoprenaline, on INa/Ca and sarcoplasmic re...

Suppression of electrical alternans may be antiarrhythmic. Our previous computer simulations have suggested that increasing the rapid component of the delayed rectifier K(+) current (I(Kr)) suppresses alternans. To test this hypothesis, I(Kr) in isolated canine ventricular myocytes was increased by infection with an adenovirus containing the gene for the pore-forming domain of I(Kr) [human ethe...

Plasma membrane-localized CaV1.2 channels are the primary calcium (Ca(2+)) influx pathway in arterial smooth muscle cells (myocytes). CaV1.2 channels regulate several cellular functions, including contractility and gene expression, but the trafficking pathways that control the surface expression of these proteins are unclear. Similarly, expression and physiological functions of small Rab GTPase...

The delayed-rectifier voltage-gated K(+) channel (Kv) 2.1 underlies the cardiac slow K(+) current in the rodent heart and is particularly interesting in that both its function and localization are regulated by many stimuli in neuronal systems. However, standard immunolocalization approaches do not detect cardiac Kv2.1; therefore, little is known regarding its localization in the heart. In the p...

Compared to sham-operated controls, myofilaments from hearts of ovariectomized (OVX) rats demonstrate an increase in Ca2+ sensitivity with no change in maximum tension (Wattanapermpool J and Reiser PJ. Am J Physiol 277: H467-H473, 1999). To test the significance of this modification in intact cells, we compared intracellular Ca2+ transients and shortening of ventricular myocytes isolated from s...

To determine whether angiotensin II (Ang II) stimulation of adult ventricular myocytes in vitro results in cellular hypertrophy, the changes in myocyte volume and protein content per cell were examined by confocal microscopy. Moreover, the possibility was considered that the upregulation of Ang II receptors on myocytes after infarction may potentiate and/or accelerate Ang II–mediated myocyte gr...

Diabetes mellitus and alcohol (ethanol) intake are two positively correlated major risk factors for cardiovascular abnormalities. However, the interaction of the two on cardiac function is largely unknown. The purpose of the present study was to examine the impact of genetically predisposed diabetes on acute ethanol exposure-induced cardiac contractile depression at the myocyte level. Ventricul...

Elevated protein kinase C βII (PKCβII) expression develops during heart failure and yet the role of this isoform in modulating contractile function remains controversial. The present study examines the impact of agonist-induced PKCβII activation on contractile function in adult cardiac myocytes. Diminished contractile function develops in response to low dose phenylephrine (PHE, 100 nM) in cont...

BACKGROUND Mammalian cardiac myocytes withdraw from the cell cycle during post-natal development, resulting in a non-proliferating, fully differentiated adult phenotype that is unable to repair damage to the myocardium, such as occurs following a myocardial infarction. We and others previously have shown that forced expression of certain cell cycle molecules in adult cardiac myocytes can promot...