French A M, Scott N C
Br J Pharmacol. 1983 Dec;80(4):655-61. doi: 10.1111/j.1476-5381.1983.tb10055.x.
Graded contractile responses of the rat vas deferens were obtained to trains containing varying numbers of pulses delivered transmurally at 500 Hz, allowing construction of pulse-response curves. In the presence of postjunctional adrenoceptor blocking drugs, these curves were displaced to the right in a parallel manner, allowing the estimation of pA2 values for the drugs. Activity of drugs at prejunctional adrenoceptors was estimated from the reduction of inhibition of the response to a second pulse delivered 3 s after trains containing different numbers of pulses. It is suggested that the technique is more physiological than others used to determine the antagonistic activity of drugs at adrenoceptors.