Abstract |
In a previous study, it was suggested that inhibition of oxidative phosphorylation in smooth muscle is accompanied by a release of Ca2+ from mitochondria (Pettersson 1983); in this investigation, the effects of 2,4-dinitrophenol (DNP) and anoxia on isometric tension in pieces of smooth muscle from rabbit colon were studied. Addition of DNP to the bathing medium elicited a transient and dose-dependent contraction with an ED50 value of 2 X 10(-4) M. The contraction was not inhibited by pretreatment with atropine (1 X 10(-6) M). The removal of external Ca2+ did not reduce the contracting action of DNP. Addition of the local anaesthetic D- mepivacaine (1 X 10(-3) M), which reduces the Ca2+ efflux through the plasma membrane of the smooth muscle cells, augmented the response to DNP. Gassing the bathing medium with 95% N2 + 5% CO2 ( anoxia) for 60 min. did not affect the basal tension, but markedly reduced the contractile response to DNP. The results indicate that DNP increased cytoplasmic Ca2+ significantly enough to induce a contraction of rabbit colon smooth muscle by a large release from an intracellular store, probably from the mitochondria. Since anoxia did not mimic the contracting action of DNP, it is suggested that a high concentration of DNP would be a more effective stimulus for mitochondrial Ca2+ release than anoxia.
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Authors | G Pettersson |
Journal | Acta pharmacologica et toxicologica
(Acta Pharmacol Toxicol (Copenh))
Vol. 57
Issue 3
Pg. 184-9
(Sep 1985)
ISSN: 0001-6683 [Print] Denmark |
PMID | 4061099
(Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
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Chemical References |
- Dinitrophenols
- Mepivacaine
- Oxygen
- Calcium
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Topics |
- Animals
- Calcium
(metabolism)
- Colon
(drug effects)
- Dinitrophenols
(pharmacology)
- In Vitro Techniques
- Isometric Contraction
(drug effects)
- Mepivacaine
(pharmacology)
- Muscle, Smooth
(drug effects)
- Oxygen
(pharmacology)
- Rabbits
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