[Kinetic of beta1-adrenergic reaction of chicken embryo amnion]

Dose-dependent curves of the inhibitory beta 1-adrenergic reaction of the chick embryo amnion were analyzed on the basis of different mathematical models. Selection of the optimal model, closest to the experimental data, allows us to obtain the reaction parameters with the smallest statistical error. Two main characteristics of the physiological reaction, EC50 and Pm, sufficed for the description of the action of agonists nonselective for beta 1-adrenoreceptors: adrenaline (EC50 0.19 +/- 0.02 microM, Pm 101.3 +/- 1.9%) and salbutamol (EC50 0.58 +/- 0.01 microM, Pm 42.7 +/- 0.3%). The Hill coefficient n in these experiments was close to 1 (1.06 +/- 0.14; 0.96 +/- 0.02). It was necessary to introduce fractional values 1 < n < 2 to describe the effects of noradrenaline and isopropyl noradrenaline.