In vitro studies of subcalyceal upper urinary tract muscle in multicalyceal kidneys.

Isolated preparations of porcine renal pelvis and ureter were investigated by an isometric technique. The majority of pelvis muscle preparations exhibited spontaneous activity as did those taken from the upper two-thirds of the ureter, whilst lower-third ureteral specimens remained inactive. By the use of some autonomic drug agonists and antagonists the presence of alpha-adrenoceptors and muscarinic receptors was demonstrated at all sites. Evidence of beta-adrenoceptor activity was noted in pelvis muscle and also in preparations from the upper two-thirds of the ureter. Results of electrical stimulation experiments with similar preparations were shown to be against the concept of any effective innervation of these receptor sites. These findings are compared with earlier studies on the calyx of the same animal, and are discussed in relation to the possibility of the calyx acting as a primary pacemaker site for the upper urinary tract in animals with multicalyceal kidneys.