Electrophysiology of the intestinal musculature

Bolton, T. B.

doi:10.1002/cphy.cp060106

Cited by 9 publications

(7 citation statements)

References 318 publications

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“…CZEO and estragole blocked ACh-, HA-, and K +induced contractions. These contractions are caused, at least in part, by release of Ca ++ from intracellular stores (Bolton, 1989). Since blockage by the two oils was achieved with similar values of IC 50 , we infer a nonspecific action regarding receptors for neurotransmitters and autacoids.…”

Section: Discussionmentioning

confidence: 81%

Effects of the essential oil ofCroton zehntneri, and its constituent estragole on intestinal smooth muscle

et al. 1997

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The effects on isolated guinea‐pig ileum of the essential oil of Croton zehntneri (CZEO) and of its main constituent estragole (57% of CZEO by weight) were studied. CZEO and estragole (0.1–100 μg/mL) decreased the tonus in 56% and 61.5%, respectively, of the muscles. At concentrations above 10 μg/mL, they induced spontaneous rhythmic movements of small amplitude (less than 11% of the potassium contraction peak to peak). At concentrations from 1 to 100 μg/mL and with similar potencies, these agents blocked the contractions induced by acetylcholine, histamine and 50 mM K+ and caused relaxation of already established potassium contractures. Tested separately, CZEO, estragole and anethole (28% of CZEO by weight) blocked the contraction induced by Ca++ in the presence of 50 mM K+, but CZEO was more potent than estragole or anethole in blocking the Ca++‐induced contractions than those induced by K+. With large increases in the agonist concentration, the action of the oils on the contractions induced by Ca++ was reversible; however, their effect on contractions induced by histamine or ACh was not. The data show that the essential oil of Croton zehntneri has an effect on intestinal smooth muscle that is predominantly antispasmodic, and attributable in part to the effect of estragole, a major constituent. © 1997 John Wiley & Sons, Ltd.

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Section: Discussionmentioning

confidence: 81%

Effects of the essential oil ofCroton zehntneri, and its constituent estragole on intestinal smooth muscle

et al. 1997

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“…The upstroke of the gallbladder smooth muscle action potential is caused by calcium influx through dihydropyridine-sensitive, voltage-dependent channels (36). These action potentials resemble those seen in the gut during slow waves but are shorter in duration and occur at higher frequency (2,23,24). In the gut, slow waves that are accompanied by spikes are directly coupled to mechanical gastrointestinal motility (27), and, in gallbladder, twitches of individual muscle bundles can be observed in coordination with spontaneous action potentials (36).…”

Section: Discussionmentioning

confidence: 99%

Cholesterol inhibits spontaneous action potentials and calcium currents in guinea pig gallbladder smooth muscle

Jennings¹,

Xu²,

Firth³

et al. 1999

American Journal of Physiology-Gastrointestinal and Liver Physi

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Elevated cholesterol decreases agonist-induced contractility and enhances stone formation in the gallbladder. The current study was conducted to determine if and how the electrical properties and ionic conductances of gallbladder smooth muscle are altered by elevated cholesterol. Cholesterol was delivered as a complex with cyclodextrin, and effects were evaluated with intracellular recordings from intact gallbladder and whole cell patch-clamp recordings from isolated cells. Cholesterol significantly attenuated the spontaneous action potentials of intact tissue. Furthermore, calcium-dependent action potentials and calcium currents were reduced in the intact tissue and in isolated cells, respectively. However, neither membrane potential hyperpolarizations induced by the ATP-sensitive potassium channel opener, pinacidil, nor voltage-activated outward potassium currents were affected by cholesterol. Hyperpolarizations elicited by calcitonin gene-related peptide were reduced by cholesterol enrichment, indicating potential changes in receptor ligand binding and/or second messenger interactions. These data indicate that excess cholesterol can contribute to gallbladder stasis by affecting calcium channel activity, whereas potassium channels remained unaffected. In addition, cholesterol enrichment may also modulate receptor ligand behavior and/or second messenger interactions.

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“…Voltage-dependent Ca 2ϩ channels have been identified in virtually all gastrointestinal smooth muscles including the stomach (33), intestine (10), and colon (19). They play a key role in action potential generation (6), modulation of slowwave activity (31), and initiation of muscle contractions (36). In the esophagus, L-type Ca 2ϩ channel current (I Ca,L ) has been studied using patch-clamp techniques in rabbit esophageal muscularis mucosae (1) and esophageal circular smooth muscle from the esophageal body of the opossum (2), cat (22,35), and human (17a).…”

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confidence: 99%

Regional differences in L-type Ca²⁺channel expression in feline lower esophageal sphincter

Muinuddin¹,

Kang²,

Gaisano³

et al. 2004

American Journal of Physiology-Gastrointestinal and Liver Physi

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In humans and cats, muscle from the lower esophageal sphincter (LES) circular region exhibits greater spontaneous tone than LES sling muscle, whereas the sling muscle is much more responsive to cholinergic stimulation. Despite physiological and pharmacological evidence for the presence of L-type Ca2+ channel current (ICa,L) activity in LES circular muscle, the identity of this channel has not been demonstrated biochemically or electrophysiologically fingerprinted. Furthermore, there is no information on the channel's presence and role in the sling region of the LES. We hypothesized that regional differences in the expression of ICa,L between LES circular and sling muscles, if present, could contribute to the functional asymmetry observed within the LES. ICa,L expression was compared between circular and sling regions of the LES by Western blot analysis. The patch-clamp technique was used to study ICa,L. Muscle strip studies assessed ICa,L contribution to contractile activity. We found both protein expression of ICa,L and ICa,L density to be greater in LES circular muscle than sling muscle. ICa,L voltage- and time-dependent activation and inactivation curves were similar in cells from both regions. ICa,L blockade with nifedipine inhibited spontaneous tone and ACh-induced contractions only in circular muscle but was able to abolish depolarization (KCl)-induced contractions in both sling and circular muscles. In contrast, La3+ inhibited tone and ACh-induced contractions in muscles from both regions. Therefore, regional myogenic differences in ICa,L expression within the LES circular and sling muscle exist and provide one explanation for the differential contribution of sling and circular muscle to LES contractility.

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Electrophysiology of the intestinal musculature

Cited by 9 publications

References 318 publications

Effects of the essential oil ofCroton zehntneri, and its constituent estragole on intestinal smooth muscle

Effects of the essential oil ofCroton zehntneri, and its constituent estragole on intestinal smooth muscle

Cholesterol inhibits spontaneous action potentials and calcium currents in guinea pig gallbladder smooth muscle

Regional differences in L-type Ca²⁺channel expression in feline lower esophageal sphincter

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Electrophysiology of the intestinal musculature

Cited by 9 publications

References 318 publications

Effects of the essential oil ofCroton zehntneri, and its constituent estragole on intestinal smooth muscle

Effects of the essential oil ofCroton zehntneri, and its constituent estragole on intestinal smooth muscle

Cholesterol inhibits spontaneous action potentials and calcium currents in guinea pig gallbladder smooth muscle

Regional differences in L-type Ca2+channel expression in feline lower esophageal sphincter

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Regional differences in L-type Ca²⁺channel expression in feline lower esophageal sphincter