Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P20020 (adenosine triphosphatase)
 3,299 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Physiological evidence suggests that muscarinic receptors mediate the secretory response of the intestinal mucosa of cholinergic agonists, but the question of whether muscarinic receptors are intrinsic to intestinal epithelial cells has remained unanswered. We therefore studied binding of the muscarinic ligand [3H]quinuclidinyl benzilate to isolated rat colonic epithelial cells. Specific binding in the membrane preparation reached equilibrium in 30 min at 37 degrees C, was linear with tissue protein concentration and was saturable. Estimates of the apparent equilibrium dissociation constant (KD) equalling 0.11 +/- 0.03 nM and of maximum receptor density (Bmax) equalling 103.6 +/- 9.0 fmol/mg of protein were determined from Scatchard plots of the binding data. The Hill coefficient for binding was 0.93 +/- 0.04. From kinetic analysis of data, association and dissociation rate constants of 8.6 X 10(7) M-1 min-1 and 6.0 X 10(-3) min-1, respectively, were calculated. Inhibition of specific binding was stereoselective and pharmacologically specific for muscarinic agents. Specific binding, vasoactive intestinal peptide-stimulated adenylate cyclase and Na+-K+-stimulated adenosine triphosphatase activities were highest in a mitochondrial-free fraction of rat colonocytes. Specific binding was lowest in the nuclear fraction, followed by the total particulate and mitochondrial fractions. The regional distribution of specific binding along the length of the intestine was also studied. Scatchard analysis revealed one specific binding site, with the same KD in the jejunum, ileum and colon. The receptor density was the same in the jejunum and ileum, but about 5-fold higher for the existence of muscarinic receptors on intestinal epithelial cells and suggest that the effects of muscarinic drugs on intestinal epithelial cell function are mediated by interaction with these receptors.
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PMID:Evidence for muscarinic receptors on rat colonic epithelial cells: binding of [3H]quinuclidinyl benzilate. 725 42

This study set out to examine in detail the distribution of axons of sympathetic non-noradrenergic neurons innervating the arterial bed in skeletal muscles of the forelimb and hindlimb of guinea-pigs. The distribution of non-noradrenergic axons with immunoreactivity to vasoactive intestinal peptide (VIP) was examined in limb muscles of different histochemical character. The immunohistochemical demonstration of myosin heavy chain from fast-twitch muscle, and the histochemical demonstration of adenosine triphosphatase and succinic dehydrogenase, were used to determine the muscle fibre profile of 6 different limb muscles. Muscles included the oxidative type I muscle fibre-rich accessory semimembranosus muscle, the predominantly glycolytic type II muscle fibre-rich cranial gracilis and biceps brachii muscles and the plantaris, gastrocnemius medial head and triceps brachii long head of mixed muscle fibre composition. The frequency with which the VIP-immunoreactive (VIP-IR) axons innervated intramuscular arterial vessels was compared between categories of muscles defined by their muscle fibre profile. This study demonstrated that the projection of non-noradrenergic sympathetic neurons to skeletal muscle vasculature was widespread in guinea-pig limb muscles, but that it was not uniform. VIP-IR axons were more likely to innervate the arterial vasculature of muscles with a high proportion of type I and/or oxidative muscle fibres than of muscles with a large proportion of type IIb muscle fibres. This relationship between the distribution of sympathetic non-noradrenergic axons and the metabolic characteristics of muscle suggests that these presumed vasodilator neurons have an important role in matching blood flow to the particular metabolic demands of different limb muscles.
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PMID:Projections of sympathetic non-noradrenergic neurons to skeletal muscle arteries in guinea-pig limbs vary with the metabolic character of muscles. 934 29