Homotaurine: a GABA<sub>B</sub> antagonist in guinea‐pig ileum

British Journal of Pharmacology - Tập 79 Số 4 - Trang 855-862 - 1983
A Giotti1, Simona Luzzi1, S. Spagnesi1, L. Zilletti1
1Istituto Interfacoltà di Farmacologia e Tossicologia, Università di Firenze, Viale G.B. Morgagni 65, 50134 Firenze, Italy

Tóm tắt

Homotaurine (3‐aminopropane sulphonic acid) did not inhibit the twitch response in guinea‐pig ileum longitudinal muscle whilst γ‐aminobutyric acid (GABA) and (−)‐baclofen evoked dose‐dependent inhibitions. The inhibitory effects of GABA and (−)‐baclofen were prevented in the presence of homotaurine 2 × 10−4 and 10−3 M. The log dose‐effect curves of GABA and (−)‐baclofen were shifted in a parallel manner compatible with competitive antagonism. The pA2 of homotaurine with GABA (4.22 ± 0.05) and (−)‐baclofen (4.26 ± 0.1) were the same. Homotaurine did not antagonize the inhibitory effects of morphine (ED50 4 × 10−7 M), noradrenaline (ED50 10−6 M) or ATP (ED50 1.5 × 10−5 M). The inferior homologue of homotaurine, taurine 10−3 M, did not modify the inhibitory effects of GABA and (−)‐baclofen. Picrotoxin 5 × 10−5 M antagonized GABAA receptor‐mediated contraction but did not affect GABAB receptor‐mediated inhibition. At the same concentration the drug did not influence the antagonistic action of homotaurine, thus showing no GABAA receptor‐mediated interference. It may be concluded that homotaurine is a competitive antagonist of GABAB mediated effects in the guinea‐pig ileum.

Từ khóa


Tài liệu tham khảo

10.1111/j.1476-5381.1974.tb08563.x

10.1016/0014-2999(81)90386-1

10.1113/jphysiol.1926.sp002315

10.1016/0006-8993(71)90156-9

CURTIS D.R., 1974, Amino acid transmitters in the mammalian central nervous system, Ergebn. Physiol., 69, 97

10.1111/j.1476-5381.1961.tb01086.x

10.1016/0006-8993(75)90243-7

10.1016/0361-9230(80)90114-8

10.1111/j.1476-5381.1983.tb08807.x

10.1038/281071a0

10.1016/0014-2999(82)90573-8

10.1111/j.1476-5381.1982.tb09282.x

10.1139/o63-294

10.1111/j.1476-5381.1969.tb07964.x

10.1113/jphysiol.1968.sp008392

10.1007/BF00508286

10.1111/j.1471-4159.1973.tb07551.x

ROSSUM J.M., 1963, Cumulative dose‐response curves. II Technique for the making of dose‐response curves in isolated organs and the evaluation of drug parameters, Archs Int. Pharmacodyn., 143, 299

Thông tin
Thông tin xuất bản

British Journal of Pharmacology

Tập 79 Số 4

855-862

Thông tin tác giả