OBJECTIVE To examine the contribution of reverse mode sodium-calcium (Na-Ca) exchange to contractions in isolated left-ventricular myocytes from failing human heart. METHODS Low resistance patch pipettes were used to dialyze cells with Na-free or high-Na pipette solution ([Na]pipette = 0 and 20 mmol/L, respectively) to reduce or enhance Na-Ca exchange. Whole-cell membrane-potential, membrane-...

BACKGROUND Despite increasing evidence for the presence of voltage-gated Na(+) channels (Na(v)) isoforms and measurements of Na(v) channel currents with the patch-clamp technique in arterial myocytes, no information is available to date as to whether or not Na(v) channels play a functional role in arteries. The aim of the present work was to look for a physiological role of Na(v) channels in th...

AIMS The aim of the present study was to investigate whether agents which enhance force of contraction via increasing intracellular Na+, i.e. cAMP-independently, remain effective in failing human myocardium. METHODS Cumulative concentration-response curves with (+/-)BDF 9148 (0.01-10 mumol l-1), a Na(+)-channel activator, and ouabain (0.01-0.1 mumol l-1), a Na+/K(+)-ATPase inhibitor, were per...

Histochemical study revealed that transcutaneous injection of ethanol into the vicinity of the pterygopalatine ganglion greatly decreased the positive staining for NADPH diaphorase activity after 1 week in the ipsilateral ganglion of a dog and abolished the staining of perivascular nerves in the middle and posterior cerebral arteries. Transmural electrical stimulation or nicotine produced a rel...

Histochemical study revealed that transcutaneous injection of ethanol into the vicinity of the pterygopalatine ganglion greatly decreased the positive staining for NADPH diaphorase activity after 1 week in the ipsilateral ganglion of a dog and abolished the staining of perivascular nerves in the middle and posterior cerebral arteries. Transmural electrical stimulation or nicotine produced a rel...

The signaling of contraction by Ca2+ in the Syrian hamster (BIO 14.6) heart in the late stage of the cardiomyopathy (220 to 300 days old) was compared with that in age-matched healthy hamster hearts. Membrane current and cell shortening or intracellular Ca2+ transients were measured simultaneously in isolated whole-cell-clamped myocytes. The density of the L-type Ca2+ current was smaller in myo...

The effects of various concentrations (0, 0.5, 1, 2, 4, and 8 mM) of potassium chloride on the simultaneously recorded action potential and contractility; and Mg++-dependent, Na++-K+-stimulated membrane ATPase of guinea pig's heart were studied. In KCl-free solution, the inhibition of the Na+-K+-ATPase was associated both with a shortening of the duration of action potential and an increase in ...

The effects of caffeine (0.2-10 mM) on the electrical and mechanical activities of guinea pig taenia coli were investigated with the double sucrose-gap method. Caffeine evoked a small tension with a latency of 20-30 sec, then phasic contraction developed and finally relaxation. The initial tension development also appeared in the Na-free solution without any marked changes in the membrane poten...

The effects of caffeine (0.2-10 mM) on the electrical and mechanical activities of guinea pig taenia coli were investigated with the double sucrose-gap method. Caffeine evoked a small tension with a latency of 20-30 sec, then phasic contraction developed and finally relaxation. The initial tension development also appeared in the Na-free solution without any marked changes in the membrane poten...

ANDREW C. UGWU1, GODFREY L. SMITH, DAVID J. MILLER AND JOHN C. MCGRATH. Autonomic Physiology Unit, Institute of Physiology, University of Glasgow, Glasgow G12 8QQ, Scotland. ____________________________________________________________________________________________________ The calcium sensitivity of vascular smooth muscle contraction and experimentally-induced desensitisation to noradrenaline ...