A comparison of responses of guinea-pig isolated trachea to six prostaglandins

Abstract

Effects of prostaglandins (PG) E1, E2, F2alpha, A1, A2 and B2 were studied on guinea-pig isolated tracheal chains. PGF2alpha, B2 and A2 produced contraction, PGE1 and E2 relaxation of the chain, but A1 produced no response. 1) From the cumulative dose response curves, PGF2alpha was more active in producing contraction than B2 or A2, though its effect was less than that of acetylcholine (ACh). PGE1-induced relaxation was less than the response to isoproterenol. 2) PGE1 and E2 1 microgram/ml caused a 26.1 +/- 3.83% (n=5) or a 9.5 +/- 3.36 (n=6) decrease of ACh (1 microgram/ml)-induced contraction respectively. The degree of relaxation produced by E1 was greater than that by E2 (P less than 0.01). 3) After five minutes preincubation with each of PGA1, A2, B2 and F2alpha in concentrations which did not produce any effect, ACh-induced contraction was augmented only after PGA2 (P less than 0.05).