NEUROMUSCULAR-TRANSMISSION AND INNERVATION IN THE URINARY-BLADDER OF THE INSECTIVORE SUNCUS-MURINUS

In isolated preparations of the urinary bladder detrusor of the house musk shrew Suncus murinus (order: insectivora; family: Soricidae), ele ctrical field stimulation (0.5-32 pulses/s) evoked neurogenic contract ile responses that were markedly attenuated by atropine (1 mu M). The non-cholinergic component was reduced but not abolished by the P-2-pur inoceptor antagonist, suramin (300 mu M). Thus, neuromuscular transmis sion in the suncus urinary bladder is effected by cholinergic and puri nergic nerves together with an as-yet unidentified component. Using im munohistochemical methods, the suncus urinary bladder was seen to be s upplied by nerves containing neuropeptide Y, tyrosine hydroxylase, vas oactive intestinal polypeptide, galanin, substance P, calcitonin gene- related peptide and type I nitric oxide synthase. The pattern of respo nses to electrical field stimulation was more similar to that of human s and Old World primates, than to that of rodents or lagomorphs. The p attern of innervation of the bladder wall, in terms of the distributio n of populations containing a given neuropeptide, was very similar to that in humans. Hence, Suncus murinus may provide a novel species for modelling the neuropharmacology of the human bladder, and also for stu dying the evolution of autonomic innervation. (C) 1998 Elsevier Scienc e B.V. All rights reserved.