THE presence of both alpha and beta adrenergic receptors has been demonstrated in the caudal third of the pig ureter by means of the technique of Trendelenburg (Deane, 1967) and in all segments of the canine ureter by means of the isometric strip technique (Malin et al., 1968). Activation of the " dominant " alpha receptors by adrenaline and noradrenaline produces a contraction of the smooth muscle. The presence of the " recessive " beta receptors can be revealed by activating the beta receptors directly, or by blocking the alpha receptors and then activating the " unblocked " beta receptors with adrenaline or noradrenaline.It has been suggested that activation of these beta adrenergic receptors during bladder contraction may give rise to vesico-ureteric reflux. This may also account for aperistaltic distal segmental dilatation of the ureter occasionally observed in patients with uretero-vesical obstruction.The aim of this present study was to examine the human ureter to determine if both alpha and beta adrenergic receptors were present.Materials and Method.-Two methods of investigation were employed. The apparatus used by R. F. D. is as described for the Trendelenburg preparation (Trendelenburg, 1917). Specimens of lower third of human ureter were obtained fresh at operation, placed in Krebs solution and transported to the laboratory. Three preparations were obtained. Two were from males and 1 from a female. In each case the bladder was the seat of fairly advanced cancer and subsequent histology of the ureter showed cancerous infiltration.J. M. M. and S . B. used the isometric strip method of investigation (Malin et al., 1968).Specimens from all levels of human ureter were obtained at operation, placed in Locke's solution and transported to the laboratory. Twenty-two normal preparations were obtained from renal transplant donors and 57 experiments were performed.Results.-Trendelenburg's Technique.-The lengths of lower third of the human ureter responded with spontaneous contractions with Trendelenburg's technique. It is presumed that the amplitude of contraction would have been greater if the tissue had not been the seat of neoplastic infiltration. Prolonged experimentation was not possible also because of the cancerous process, the preparation becoming easily fatigued.Only the changes in length are recorded for convenience but the volume change closely followed the changes in length (Fig. 1).Adrenaline hydrochloride at a concentration of 10-5 g./ml. of the salt and L-noradrenaline bitartrate at a concentration of 10-6 g./ml. of the salt both increase the tone and frequency of contraction.Isoprenaline (isoproterenol or D, L-N-Isopropylnoradrenaline), at a concentration of 10-5 g./ml. of the base decreased the amplitude and frequency of contraction.
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