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Extracellular Ca2+ mobilization in potential-dependent contraction of trachealis of maturing swine.
- Source :
-
Journal of applied physiology (Bethesda, Md. : 1985) [J Appl Physiol (1985)] 1991 Oct; Vol. 71 (4), pp. 1489-95. - Publication Year :
- 1991
-
Abstract
- We studied the effect of maturation on potassium-induced parasympathetic activation and Ca2+ entry in tracheal smooth muscle (TSM) from fifteen 2-wk-old (2ws) and sixteen 10-wk-old (10ws) male domestic farm swine. Atropine (10(-7) M) caused inhibition of the maximal contraction elicited by potassium to 50.3 +/- 2.6% maximum of control response (P less than 0.001) in TSM from 2ws but had no significant effect in TSM from 10ws (94.6 +/- 4.2% maximum; P = NS vs. control). Verapamil (10(-7) M) plus 10(-7) M atropine reduced contraction elicited by potassium in both 2ws (23.7 +/- 5.8% maximum; P less than 0.001 vs. control) and 10ws (50.6 +/- 6.3% maximum; P less than 0.001 vs. control, P less than 0.05 vs. 2ws); 10(-6)M verapamil caused greater than 95% blockade of contraction caused by potassium in both 2ws and 10ws. In separate studies, atropine-treated strips were equilibrated with extracellular Ca2+ concentrations ([Ca2+]o) ranging from normal (1X [Ca2+]o) to four times normal (4x [Ca2+]o). Increasing [Ca2+]o increased maximal contractile response in atropine-treated TSM strips from 68.7 +/- 3.8% maximum for 1x [Ca2+]o to 100.8 +/- 4.8% maximum for 4x [Ca2+]o (P less than 0.001) in 2ws. Neither atropine nor [Ca2+]o affected maximal responses of TSM in 10ws (103.5 +/- 3.0% maximum for 1x [Ca2+]o; P = NS vs. control). However, in the presence of atropine and verapamil, 4x [Ca2+]o augmented KCl-elicited contraction of TSM from both 2ws (46.9 +/- 6.3% maximum; P less than 0.01 vs. control) and 10ws (78.6 +/- 2.3% maximum; P less than 0.005 vs. control).(ABSTRACT TRUNCATED AT 250 WORDS)
- Subjects :
- Animals
Atropine pharmacology
Calcium Channel Blockers pharmacology
Extracellular Space physiology
Male
Muscle Contraction drug effects
Muscle Contraction physiology
Parasympathetic Nervous System drug effects
Parasympatholytics pharmacology
Potassium Chloride pharmacology
Swine
Trachea growth & development
Trachea physiology
Verapamil pharmacology
Calcium physiology
Muscle, Smooth physiology
Subjects
Details
- Language :
- English
- ISSN :
- 8750-7587
- Volume :
- 71
- Issue :
- 4
- Database :
- MEDLINE
- Journal :
- Journal of applied physiology (Bethesda, Md. : 1985)
- Publication Type :
- Academic Journal
- Accession number :
- 1757374
- Full Text :
- https://doi.org/10.1152/jappl.1991.71.4.1489