Intravenous administration of methacholine (200 micrograms/kg) caused no changes in the seminiferous tubules of rats, but significantly increased intraluminal pressures and contractility of the caput, the corpus and the cauda epididymidis. The effect of methacholine was abolished by pretreatment with atropine (500 micrograms/kg), but not by phentolamine (400 micrograms/kg) or propranolol (400 micrograms/kg). Adrenaline (5-40 micrograms/kg), noradrenaline (5-40 micrograms/kg) and phenylephrine (100-400 micrograms/kg) had no effect on the seminiferous tubules, but dose-dependently elevated intraluminal pressures and enhanced the contractility of all regions of the epididymis. Isoproterenol (100-800 micrograms/kg) did not affect intraluminal pressures of the seminiferous tubules and the epididymal duct. The stimulatory effect of adrenergic agonists was specifically blocked by phentolamine, but not by propranolol or atropine. Cholinergic and adrenergic antagonists did not alter spontaneous contraction of the epididymis. The results suggest that the contractility of all segments of the rat epididymis, but not the seminiferous tubules, can be increased by autonomic drugs. The enhancing effect of adrenergic drugs is probably the result of activation through alpha-adrenergic receptors.

Intraluminal pressures in the seminiferous tubules and in various regions along the epididymis of the rat were measured by micropuncture using a servo-nulling pressure transducer system. The intraluminal hydrostatic pressure in the testis was significantly lower than that in all regions of the epididymis. There was an increasing pressure gradient from the caput to the cauda epididymidis. Spontaneous contractions were observed in all parts of the epididymis but not in the seminiferous tubules. The amplitude of contraction in the epididymis increased from the caput to the proximal cauda. However, an appreciable decrease in the amplitude occurred in the distal cauda, although the frequency of contraction declined from the proximal caput to the distal cauda with substantial reductions in the mid-caput and the proximal cauda.