Autonomic Modification of Intestinal Smooth Muscle Contractility

Autor/inn/en	Montgomery, Laura E. A.; Tansey, Etain A.; Johnson, Chris D.; Roe, Sean M.; Quinn, Joe G.
Titel	Autonomic Modification of Intestinal Smooth Muscle Contractility
Quelle	In: Advances in Physiology Education, 40 (2016) 1, S.104-109 (6 Seiten)Infoseite zur Zeitschrift PDF als Volltext Verfügbarkeit
Sprache	englisch
Dokumenttyp	gedruckt; online; Zeitschriftenaufsatz
ISSN	1043-4046
DOI	10.1152/advan.00038.2015
Schlagwörter	Human Body; Motor Reactions; Physiology; Pharmacology; Science Activities; College Science; Science Instruction; Undergraduate Students; Foreign Countries; United Kingdom + Suchen Sie Ihr Suchwort? Menschlicher Körper; Physiologie; Arzneikunde; Teaching of science; Science education; Natural sciences Lessons; Naturwissenschaftlicher Unterricht; Ausland; Großbritannien
Abstract	Intestinal smooth muscle contracts rhythmically in the absence of nerve and hormonal stimulation because of the activity of pacemaker cells between and within the muscle layers. This means that the autonomic nervous system modifies rather than initiates intestinal contractions. The practical described here gives students an opportunity to observe this spontaneous activity and its modification by agents associated with parasympathetic and sympathetic nerve activity. A section of the rabbit small intestine is suspended in an organ bath, and the use of a pressure transducer and data-acquisition software allows the measurement of tension generated by the smooth muscle of intestinal walls. The application of the parasympathetic neurotransmitter ACh at varying concentrations allows students to observe an increase in intestinal smooth muscle tone with increasing concentrations of this muscarinic receptor agonist. Construction of a concentration-effect curve allows students to calculate an EC[subscript 50] value for ACh and consider some basic concepts surrounding receptor occupancy and activation. Application of the hormone epinephrine to the precontracted intestine allows students to observe the inhibitory effects associated with sympathetic nerve activation. Introduction of the drug atropine to the preparation before a maximal concentration of ACh is applied allows students to observe the inhibitory effect of a competitive antagonist on the physiological response to a receptor agonist. The final experiment involves the observation of the depolarizing effect of K[superscript +] on smooth muscle. Students are also invited to consider why the drugs atropine, codeine, loperamide, and botulinum toxin have medicinal uses in the management of gastrointestinal problems. (As Provided).
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Erfasst von	ERIC (Education Resources Information Center), Washington, DC
Update	2020/1/01