The effect of Mn2+, Zn2+, Ba2+ and Ca2+ on spontaneous motility in sheep duodenum in vitro

1. The effects of several ions, Mn2+, Zn2+, Ba2+ and Ca2+, on spontaneous motility were investigated in longitudinal smooth muscle strips from sheep duodenum, in vitro. 2. Mn2+ (0.5-1.5 mM) and Zn2+ (0.5-5 mM) inhibited both the amplitude and frequency of motility in Krebs solution and in Ca(2+)-fre...

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Bibliographic Details
Published in:General pharmacology 1997, Vol.28 (1), p.65-71
Main Authors: MURILLO, M. D, PLAZA, M. A, ARRUEBO, M. P
Format: Article
Language:English
Subjects:
Animals
Barium - pharmacology
Biological and medical sciences
Calcium - pharmacology
Calcium Channels - metabolism
Cations, Divalent - pharmacology
Duodenum - physiology
Fundamental and applied biological sciences. Psychology
Gastrointestinal Motility - drug effects
In Vitro Techniques
Intestine. Mesentery
Manganese - pharmacology
Muscle Contraction - drug effects
Muscle, Smooth - drug effects
Sheep
Vertebrates: digestive system
Zinc - pharmacology
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Summary:1. The effects of several ions, Mn2+, Zn2+, Ba2+ and Ca2+, on spontaneous motility were investigated in longitudinal smooth muscle strips from sheep duodenum, in vitro. 2. Mn2+ (0.5-1.5 mM) and Zn2+ (0.5-5 mM) inhibited both the amplitude and frequency of motility in Krebs solution and in Ca(2+)-free medium. 3. Ba2+ (0.5-5 mM) evoked three types of contractile responses: (i) an increase in the frequency and a reduction of the amplitude of spontaneous contractions; (ii) a slight increase in muscle tone of the phasic contractions; and (iii) a rapid initial phasic contraction followed by slowly fading contraction. Ca2+ induced two kinds of responses in spontaneous motility: (i) a fast phasic contraction, followed by an increase in the amplitude and frequency of phasic contractions with no changes in its tone; and (ii) an increase in the amplitude of contractions. 4. The Ba(2+)-induced contractions were inhibited by EDTA, verapamil and diltiazem, but were not modified by sodium nitroprusside. The Ca(2+)-induced contractions were reduced by verapamil and diltiazem. 5. Our results show that Mn2+ and Zn2+ behave as inhibitors of sheep duodenum motility. In contrast, Ba2+ and Ca2+ stimulate motility. It is suggested that Ba2+ can penetrate the cells through voltage-dependent Ca2+ channels and behave as a partial substitute for Ca2+.
ISSN:0306-3623
1879-0011
DOI:10.1016/S0306-3623(96)00162-0