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1. Electrical events and intracellular calcium concentration ([Ca2+]) imaged using fluo-3 and laser scanning confocal microscopy were simultaneously monitored in single smooth muscle cells freshly isolated from guinea-pig vas deferens or urinary bladder. 2. Images obtained every 8 ms, during stepping from -60 to 0 or +10 mV for 50 ms under voltage clamp,(More)
Single-channel studies were made using the patch-clamp technique of K channels in dispersed single smooth muscle cells from rabbit longitudinal jejunal muscle and guinea-pig small (less than 0.2 mm o.d.) mesenteric arteries. In isolated inside-out patches from these two types of smooth muscle cell there was a population of K channels which had(More)
1. Whole-cell membrane current recordings under voltage clamp were made at room temperature from dispersed single cells of longitudinal smooth muscle of rabbit jejunum and dispersed single smooth muscle cells of rabbit ear artery using patch pipettes containing up to 10 mM-EGTA Ca buffer. 2. Spontaneous transient outward currents (s.t.o.c.s) up to 250 pA in(More)
Acetylcholine, the major excitatory neurotransmitter to the smooth muscle of mammalian intestine, is known to depolarize smooth muscle cells with an apparent increase in membrane conductance. However, the ionic mechanisms that are triggered by muscarinic receptor activation and underlie this response are poorly understood, due in part to the technical(More)
1. Voltage-dependent properties of muscarinic receptor cationic current activated by carbachol in single smooth muscle cells have been studied using patch-clamp recording techniques. Cells were obtained by enzymic digestion from the longitudinal muscle layer of guinea-pig small intestine. 2. The inward cationic current showed a pronounced U-shaped(More)
Spontaneous transient outward currents (STOCs) lasting about 100 ms occur in single smooth muscle cells and represent the simultaneous opening of up to a hundred calcium-activated potassium (BK) channels. The recent observation of brief focal releases of sarcoplasmic reticulum (SR) calcium ('sparks') in smooth muscle cells has provided support for the(More)
The interaction of Ba2+ and TEA with Ca2+-activated K+ channels was studied in isolated membrane patches of cells from longitudinal jejunal smooth muscle of rabbit and from guinea-pig small mesenteric artery (100 micron external diameter). Ba2+ applied from the inside of the membrane did not reduce unit current, except at high concentrations, but channels(More)
In longitudinal muscle of guinea-pig ileum, activation of muscarinic receptors causes contraction antagonised by M3 receptor subtype antagonists despite a preponderance of M2 receptor subtype binding sites. Experiments on single smooth muscle cells under voltage-clamp described here show that the cationic current evoked by carbachol which normally causes(More)
1. The resting membrane potential of freshly purified normodense human eosinophils bathed in and dialysed with quasi-physiological solutions was -63 +/- 2 mV (n = 100). 2. In voltage-clamp mode with quasi-physiological internal and external solutions, voltage steps from the holding potential of -60 mV to levels positive to +20 mV resulted in development of(More)
(1) The effects on the whole-cell carbachol-induced muscarinic cationic current (mIcat) of antibodies against the alpha-subunits of various G proteins, as well as the effect of a Gbetagamma subunit, were studied in single guinea-pig ileal smooth muscle cells voltage-clamped at -50 mV. Ionized intracellular calcium concentration, [Ca(2+)](i), was clamped at(More)