The relaxing effect of SCH 23390 in the molluscan smooth muscle

The present studies were carried out in an attempt to resolve the controversy about the Na+ dependence of beta-adrenergic relaxation in smooth muscle. Previous studies on isolated smooth muscle cells from the toad stomach had suggested that at least some of the actions of beta-adrenergic agents, including a stimulatory effect on 45Ca efflux, were dependent on the presence of a normal transmembrane Na+ gradient. Studies by other investigators using tissues derived from mammalian sources had suggested that the relaxing effect of beta-adrenergic agents was Na+ independent. Uncertainty remained as to whether these discrepancies reflected differences between cells and tissues or differences between species. Thus, in the present studies, we utilized both tissues and cells from the same source, the stomach muscle of the toad Bufo marinus, and assessed the Na+ dependence of beta-adrenergic relaxation. We found that elimination of a normal Na+ gradient abolished beta-adrenergic relaxation of isolated cells. In tissues, however, similar manipulations had no effect on relaxation. The reasons for this discrepancy are unclear but do not appear to be attributable to changes in smooth muscle function following enzymatic dispersion. Rather they may be attributable to unique properties of tissues, such as the presence of pacemaker cells, nerves, and so on. Thus the controversy concerning the mechanism of beta-adrenergic relaxation may reflect inherent differences between tissues and cells.

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Neural regulation of in vitro giant contractions in the rat colon

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.2001.281.1.g275 ◽

2001 ◽

Vol 281 (1) ◽

pp. G275-G282 ◽

Cited By ~ 27

Author(s):

Asensio Gonzalez ◽

Sushil K. Sarna

Keyword(s):

Smooth Muscle ◽

Smooth Muscle Cells ◽

Sch 23390 ◽

Circular Muscle ◽

Electrical Field Stimulation ◽

Muscle Cells ◽

Enteric Neurons ◽

Rat Colon ◽

Spontaneous Contractions

The rat middle colon spontaneously generates regularly occurring giant contractions (GCs) in vitro. We investigated the neurohumoral and intracellular regulation of these contractions in a standard muscle bath. cGMP content was measured in strips and single smooth muscle cells. The circular muscle strips generated spontaneous GCs. Their amplitude and frequency were significantly increased by tetrodotoxin (TTX), ω-conotoxin, N ω-nitro-l-arginine (l-NNA), and the dopamine D1 receptor antagonist Sch-23390. The GCs were unaffected by hexamethonium, atropine, and antagonists of serotonergic (5-HT1–4), histaminergic (H1–2), and tachykininergic (NK1–2) receptors but enhanced by NK3receptor antagonism. The guanylate cyclase inhibitor 1H-[1,2,4]oxidiazolo[4,3-a]quinoxalin-1-one (ODQ) also enhanced GCs to the same extent as TTX and l-NNA, and each of the three agents prevented the effects of the others. GCs were abolished by electrical field stimulation, S-nitroso- N-acetyl-penicillamine, and 8-bromo-cGMP. BAY-K-8644 and apamin enhanced the GCs, but they were abolished by D-600. Basal cGMP content in strips was decreased by TTX,l-NNA, or ODQ, but these treatments had no effect on cGMP content of enzymatically dissociated single smooth muscle cells. We conclude that spontaneous contractions in the rat colonic muscle strips are not generated by cholinergic, serotonergic, or histaminergic input. Constitutive release of nitric oxide from enteric neurons sustains cGMP synthesis in the colonic smooth muscle to suppress spontaneous in vitro GCs.

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Effects of Ca-antagonists and antispasmodic drugs on ACh-contraction in molluscan smooth muscle

The Japanese Journal of Pharmacology ◽

10.1016/s0021-5198(19)62704-6 ◽

1984 ◽

Vol 36 ◽

pp. 249

Author(s):

Hajime Murakami ◽

Toshinori Ishikawa

Keyword(s):

Smooth Muscle ◽

Molluscan Smooth Muscle

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The relaxing effect of aluminum and lanthanum on rat and human gastric smooth muscle in vitro

European Journal of Pharmacology ◽

10.1016/0014-2999(73)90006-x ◽

1973 ◽

Vol 22 (2) ◽

pp. 156-161 ◽

Cited By ~ 32

Author(s):

Milos Hava ◽

Aryeh Hurwitz

Keyword(s):

Smooth Muscle ◽

Gastric Smooth Muscle ◽

Relaxing Effect

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The Vasorelaxant Effect ofp-Cymene in Rat Aorta Involves Potassium Channels

The Scientific World JOURNAL ◽

10.1155/2015/458080 ◽

2015 ◽

Vol 2015 ◽

pp. 1-6 ◽

Cited By ~ 6

Author(s):

Martapolyana T. M. Silva ◽

Fernanda P. R. A. Ribeiro ◽

Maria Alice M. B. Medeiros ◽

Pedrita A. Sampaio ◽

Yonara M. S. Silva ◽

...

Keyword(s):

Smooth Muscle ◽

Potassium Channels ◽

Vascular Smooth Muscle ◽

Channel Blocker ◽

Antimicrobial Activities ◽

Rat Aorta ◽

Relaxant Effect ◽

Vasorelaxant Effect ◽

Dose Dependent ◽

Relaxing Effect

The monoterpenes are the main constituents of most essential oils andp-cymene is a monoterpene commonly found in various species of aromatic herbs, which has been reported for anti-inflammatory, antinociceptive, and antimicrobial activities. However, there is no report concerning its pharmacological activity on the vascular smooth muscle. The aim of current work was to investigate the effects ofp-cymene in isolated rat aorta and also study its mechanism of action. In this work, we show thatp-cymene has a relaxant effect, in a dose-dependent way, on the vascular smooth muscle, regardless of the presence of the endothelium. Using a nonselective potassium channel blocker, the CsCl, the relaxant effect ofp-cymene was attenuated. In the presence of more selective potassium channels blockers, such as TEA or 4-AP, no change in the relaxant effect ofp-cymene was evidenced, indicating thatBKCaandKVchannels are not involved in that relaxant effect. However, in the presence of glibenclamide or BaCl2,KATPandKirblockers, respectively, the relaxant effect ofp-cymene was attenuated. The data presented indicate thatp-cymene has a relaxing effect on rat aorta, regardless of the endothelium, but with the participation of theKATPandKirchannels.

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