Portal de Periódicos da CAPES

Action of colchicine on cholinergic and adrenergic mechanisms in guinea pig vas deferens

1981; Elsevier BV; Volume: 28; Issue: 8 Linguagem: Inglês

10.1016/0024-3205(81)90046-1

1879-0631

Kunio Takeyasu, Fumiaki Hata, Shuji Uchida, Hiroshi Higuchi, Hiroshi Yoshida,

Cholinesterase and Neurodegenerative Diseases

Guinea pig vas deferens responds to externally applied acetylcholine (ACh) or noradrenaline (NA) by a small rapid contraction (phasi phase) and then a large contraction (tonic phase). The phasic phase was not affected by removal of external Ca2+, but tonic phase depended on external Ca2+. At lower temperatures the two components became larger and detectable separately. The tonic phase induced by ACh at low temperature (at 20°C) was greatly depressed by brief treatment with colchicine (0.5 μM – 5 μM), although the tonic phase at high temperature (at 37°C) was not affected. Na-induced contraction (phasic or tonic phase) was not changed by the colchicine-treatment. High K+ (40 mM)-contracture, which in many cases consisted of a single phase and depended on external Ca2+, was also not affected by brief treatment with colchicine. Culture of vas deferens for 3 days in the presence of colchicine, increased the phasic phase of ACh- and NA-induced contractions significantly, but reduced the tonic phase of contractions induced by ACh and NA. Colchicine also reduced high K+-contracture, the decrease depending on the period of culture with colchicine. Organ culture with colchicine did not affect the amounts of m-ACh and α-Ad receptors or the IC50 value of ACh and NA on 3H-ligand binding. These results suggest that colchicine specifically interacts with some steps in m-ACh and α-Ad receptor-responsor (e.g. ionophore) coupling without affecting the receptor number or affinity of the receptors for agonists. The mechanisms of action of colchicine are discussed in relation to m-ACh and α-Ad receptor functions.