Effect of neuronal uptake inhibitors on the adrenergic-neuron blockade produced by guanethidine in rabbit vas deferens.

The effect of neuronal-uptake inhibitors on the guanethidine-induced inhibition of responses of rabbit vas deferens to transmural stimulation was investigated. The twitch and sustained responses were inhibited by about 70% by 1.2 X 10(-5) M guanethidine.

The potentiating effects of 4-aminopyridine on adrenergic transmission in the rabbit vas deferens.

The effects of 4-aminipyridine on adrenergic transmission in rabbit vas deferens were investigated. 10(-5)-10(-3) M 4-aminopyridine markedly potentiated the sustained, secondary contractile response to transmural stimulation and significantly increased the amount of (+/-)-|3H]-metaraminol released at 5 Hz, but had little effect on responses to exogenous (-)-noradrenaline. 10(-5)-10(-4) M 4-aminopyridine did not significantly alter the accumulation or efflux of (-)-[3H]-noradrenaline in rabbit heart.

Characteristics of accumulation of ephedrine in rabbit atria.

The characteristics of uptake of (not equal to)-(beta-14C)ephedrine were studied in isolated rabbit atria. Ephedrine was rapidly accumulated against the concentration gradient. From 5 X 10-7 to 10-2 M, uptake occurred at a uniform initial rate.