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Intracellular recordings were made from myenteric neurons of the guinea-pig distal colon to determine their electrical behaviour in response to intracellular current injection and stimulation of synaptic inputs. The recording microelectrode contained the intracellular marker biocytin, which was injected into impaled neurons so that electrophysiology, shape(More)
The distribution of nerve cells and fibres with immunoreactivity for the calcium-binding protein, calretinin, was studied in the distal colon of the guinea-pig. The projections of the neurons were determined by examining the consequences of lesioning the myenteric plexus. Calretinin-immunoreactive neurons comprised 17% of myenteric nerve cells and 6% of(More)
1. These studies describe the functional effects of modulation of the sarcoplasmic reticulum (SR) Ca2+ stores at three levels of the vasculature: (i) large arteries (rat and guinea-pig aorta); (ii) small resistance arteries (rat tail artery, rabbit mesenteric artery, dog mesenteric artery); and (iii) arterioles (guinea-pig submucosal arterioles of the small(More)
Thapsigargin and ryanodine are proposed to interfere with Ca2+ storage in sarcoplasmic reticulum by different mechanisms. Thapsigargin inhibits Ca2+ transport into and ryanodine enhances Ca2+ out of the sarcoplasmic reticulum. Contractility studies were performed in the rat aorta and dog mesenteric artery. Ryanodine was found to reduce phenylephrine-induced(More)
The objective of this study was to compare the properties of single smooth muscle cells enzymatically dispersed from the dog mesenteric arteries to the properties of similar cells functioning in tissue strips. The isolated cells remained relaxed in nominally Ca(2+)-free medium for about 1-2 h after exposure to 1 mM Ca2+ and like intact mesenteric artery(More)
1. We investigated the nature of the adrenoceptors in the dog saphenous vein (DSV) and dog mesenteric vein (DMV) to determine the nature of the unexpected interactions of phenylephrine and methoxamine with rauwolscine in the DSV, i.e. the ability of the putative alpha 2-adrenoceptor antagonist to inhibit competitively contractions to these alpha 1-agonists.(More)
We wanted to determine which alpha-adrenoceptor subtypes mediate phenylephrine (PE) contraction of dog mesenteric artery in vitro. We studied antagonisms in response to prazosin, 2-(2, 6-dimethoxyphenoxyethyl)-aminomethyl-1,4-benzodioxane, 5-methylurapidil, N-[2-(2-cyclopropyl methoxy phenoxy)ethyl]5-chloro-alpha,alpha-dimethyl-1H-indole-3-ethanamine HCl(More)
The distribution of [3H]ryanodine binding in subcellular fractions isolated from rat vas deferens (RVD) paralleled that of NADPH cytochrome C reductase activity indicating an endoplasmic reticulum origin of the binding sites. Scatchard analysis of [3H] ryanodine binding indicated an homogenous site with a Kd value of 6.4 nM. The maximum number of ryanodine(More)
Thapsigargin (TSG), a putative selective Ca(++)-ATPase inhibitor, has been used to study Ca++ mobilization in many non-excitable cell types. This study aims to determine whether TSG is effective as a selective microsomal Ca++ uptake inhibitor by studying its ability to affect repletion of the phenylephrine (PE)-sensitive Ca++ pool in rat aorta and dog(More)