Effects of Field Stimulation on Cholinergic Fibers of the Pelvic Region in the Isolated Guinea Pig Ureter

Abstract

Electrical activities have been recorded in a preparation consisting of the pelvic region and the upper ureter of the guinea pig.Train tentials followed by a multiphasic smooth muscle action potential after a latency of about 2.5-8.0 sec.This smooth muscle response was abolished by tetrodotoxin and dibucaine,and also by cholinergic blocking agents.The response was,furthermore,inhibited by decreasing Ca2+concentration and increasing Mg2+concentration in Tyrode solution.This is therefore considered to be the response synaptically evoked by cholinergic fibers in the pelvic region. Mechanical activities have been investigated on the same preparations by the Magnus method.Acetylcholine(10-7-10-4g/ml)produced a group of twitch responses which were antagonized by cholinergic blocking agents.The responsiveness of the preparations to acetylcholine was markedly decreased by removal of the pelvic region. Cholinesterase activities in the calyx-pelvis and upper ureter have been estimated by the biochemical method.A preparation consisting of calyx-pelvis exhibited twice the enzyme activity as compared with the upper ureter. These results suggested that there is a cholinergic innervation in the pelvic region of the guinea pig ureter which also takes part in control of the ureteric activity.Although many physiological and pharmacological studies on the ureteral function have been undertaken by various authors,the role of autonomic nervous system in the function of the ureter is not fully understood and controversial questions remain.Electron microscopic and histochemical studies showed the existence of cholinergic and adrenergic nerves along the entire length of the ureter (DUARTE-ESCALANTE et al.,1969;ELBADAWI and SCHENK,1969).On the other

Autonomic and sensory nerve modulation of peristalsis in the upper urinary tract

“…Exogenous application of acetylcholine increases contractility in the pig (Sorensen et al, 1983) and guinea pig (Santicioli and Maggi, 1998) renal pelvis and in the pig (Hernandez et al, 1993), human (Long and Nergardh, 1978) and guinea-pig (Yoshida and Kuga, 1980) ureter, but has little effect on the conscious porcine distal ureter (Roshani et al, 2003). Carbachol also decreases ureteric pressure and peristalsis in partially or completely obstructed ureters of anaesthetised dogs in a manner unaffected by muscarinic antagonists (Tomiyama et al, 2004).…”

Effects of field stimulation on submucosal plexus in the isolated guinea pig ureter.

“…The experiments were carried out in an Acrylite chamber (YOSHIDA and KUGA, 1980).Two pairs of electrodes were used in the chamber for stimulating and recording,and they were separated by an electrode for earthing.All these electrodes were of platinum wire 0.4mm diameter.The pelvic region of the prepa- The responses of the smooth muscle to the various agents described above were the same as those observed in the normal preparation previously reported (YOSHIDA and KUGA,1980).In addition,the physiological properties of the nerve in the normal preparation.They were as follows:chronaxie,0.40-0.45msec; absolute refractory period,2.0-2.5msec;relative refractory period,about 6msec; conduction velocity,120cm/sec (YOSHIDA and KUGA,1977).These facts indicate the possibility that the same fibers as those in the adventitial layer exist also in the submucosal layer.…”