Cytochalasin-B and phloretin depress contraction and relaxation of aortic smooth muscle

Peter E. Dresel; Leah Knickle

doi:10.1016/0014-2999(87)90514-0

Cytochalasin-B and phloretin depress contraction and relaxation of aortic smooth muscle

Peter E. Dresel, Leah Knickle

Medicine

Medicine

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8 Citas (Scopus)

Resumen

Cytochalasin-B (20 μM) and phloretin (100 μM) blocked by more than 80% the contractile responses to calcium ions in partially depolarized rabbit aortic strips. Both also blocked, but only by approximately 50%, the responses to noradrenaline and histamine in normal calcium medium. The responses to these agonists in calcium-free EGTA medium were also blocked partially. Cytochalasin-B partially blocked the acetylcholine-induced relaxation of aortic strips precontracted with phenylephrine but not the relaxation due to nitroglycerine or compound A 23187. The relaxation due to isoprenaline was potentiated by cytochalasin B. Since both compounds are known to block hexose transport but share no other known effects, it is suggested that a glycolytic intermediate could be required for the contraction in response to calcium. However, the concentrations of cytochalasin-B required for these effects were somewhat greater than those usually required to block hexose transport.

Idioma original	English
Páginas (desde-hasta)	153-157
Número de páginas	5
Publicación	European Journal of Pharmacology
Volumen	144
N.º	2
DOI	https://doi.org/10.1016/0014-2999(87)90514-0
Estado	Published - dic. 1 1987

Nota bibliográfica

Funding Information:
We have recently reported that cytochalasin-B (cyto-B) and phloretin (phlor) block the inotropic effect of digitalis and of compound BAY K-8644, an inotropic drug which holds open the calcium channels in cardiac muscle (Dresel and Ogbaghebriel, 1986; Dresel, 1986). Neither drug alone had any significant effect on isolated rabbit atria and papillary muscles. Although cyto-B caused a small change in K D for nitrendipine binding, we concluded that much of the activity of the two drugs could best be accounted for by a 'post-receptor' effect. We suggest that a mechanism requiring glucose is involved because the only known shared effect of the drugs is blockade i Aided by grants from the Medical Research Council of Canada and the Nova Scotia Heart Foundation. * To whom all correspondence should be addressed.

ASJC Scopus Subject Areas

Pharmacology

PubMed: MeSH publication types

Journal Article
Research Support, Non-U.S. Gov't

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10.1016/0014-2999(87)90514-0

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title = "Cytochalasin-B and phloretin depress contraction and relaxation of aortic smooth muscle",

abstract = "Cytochalasin-B (20 μM) and phloretin (100 μM) blocked by more than 80% the contractile responses to calcium ions in partially depolarized rabbit aortic strips. Both also blocked, but only by approximately 50%, the responses to noradrenaline and histamine in normal calcium medium. The responses to these agonists in calcium-free EGTA medium were also blocked partially. Cytochalasin-B partially blocked the acetylcholine-induced relaxation of aortic strips precontracted with phenylephrine but not the relaxation due to nitroglycerine or compound A 23187. The relaxation due to isoprenaline was potentiated by cytochalasin B. Since both compounds are known to block hexose transport but share no other known effects, it is suggested that a glycolytic intermediate could be required for the contraction in response to calcium. However, the concentrations of cytochalasin-B required for these effects were somewhat greater than those usually required to block hexose transport.",

author = "Dresel, {Peter E.} and Leah Knickle",

note = "Funding Information: We have recently reported that cytochalasin-B (cyto-B) and phloretin (phlor) block the inotropic effect of digitalis and of compound BAY K-8644, an inotropic drug which holds open the calcium channels in cardiac muscle (Dresel and Ogbaghebriel, 1986; Dresel, 1986). Neither drug alone had any significant effect on isolated rabbit atria and papillary muscles. Although cyto-B caused a small change in K D for nitrendipine binding, we concluded that much of the activity of the two drugs could best be accounted for by a 'post-receptor' effect. We suggest that a mechanism requiring glucose is involved because the only known shared effect of the drugs is blockade i Aided by grants from the Medical Research Council of Canada and the Nova Scotia Heart Foundation. * To whom all correspondence should be addressed.",

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PY - 1987/12/1

Y1 - 1987/12/1

N2 - Cytochalasin-B (20 μM) and phloretin (100 μM) blocked by more than 80% the contractile responses to calcium ions in partially depolarized rabbit aortic strips. Both also blocked, but only by approximately 50%, the responses to noradrenaline and histamine in normal calcium medium. The responses to these agonists in calcium-free EGTA medium were also blocked partially. Cytochalasin-B partially blocked the acetylcholine-induced relaxation of aortic strips precontracted with phenylephrine but not the relaxation due to nitroglycerine or compound A 23187. The relaxation due to isoprenaline was potentiated by cytochalasin B. Since both compounds are known to block hexose transport but share no other known effects, it is suggested that a glycolytic intermediate could be required for the contraction in response to calcium. However, the concentrations of cytochalasin-B required for these effects were somewhat greater than those usually required to block hexose transport.

AB - Cytochalasin-B (20 μM) and phloretin (100 μM) blocked by more than 80% the contractile responses to calcium ions in partially depolarized rabbit aortic strips. Both also blocked, but only by approximately 50%, the responses to noradrenaline and histamine in normal calcium medium. The responses to these agonists in calcium-free EGTA medium were also blocked partially. Cytochalasin-B partially blocked the acetylcholine-induced relaxation of aortic strips precontracted with phenylephrine but not the relaxation due to nitroglycerine or compound A 23187. The relaxation due to isoprenaline was potentiated by cytochalasin B. Since both compounds are known to block hexose transport but share no other known effects, it is suggested that a glycolytic intermediate could be required for the contraction in response to calcium. However, the concentrations of cytochalasin-B required for these effects were somewhat greater than those usually required to block hexose transport.

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Cytochalasin-B and phloretin depress contraction and relaxation of aortic smooth muscle

Resumen

Nota bibliográfica

ASJC Scopus Subject Areas

PubMed: MeSH publication types

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