The Effects of Parathyroid Hormone-related Protein (PTHrP) (1-34) on the Detrusor Muscle Contraction of Rabbits / 대한비뇨기과학회지

ABSTRACT

Purpose: We have studied the effect of Parathyroid hormone-related protein (PTHrP) (1-34) on the contraction of bladder muscle induced by various stimulations. MATERIALS AND METHODS: Bladder muscle strips were prepared from the urinary bladder obtained from male New Zealand White rabbits (2-2.5Kg, n=20). The isometric contractile force responses were monitored via a FT03 force transducer. PTHrP (1-34) was introduced in spontaneous contraction, carbachol (CCh) (0.5microM)-induced the contraction, and a high potassium solution (60mM) induced the contraction to monitor the responses. In addition, the effect of PTHrP (1-34) was monitored in the pre-treatment of a calcium channel blocker, nicardipine. RESULTS: PTHrP (1-34) (10 10-10 7M) reduced most of the basal spontaneous contractile responses. According to the increasing concentration, PTHrP (1-34) (10 10 -10 7M) reduced 64.6+/-8.4% of the CCh (0.5microM) induced contractions, and 34.3+/-17.4% of the high concentration potassium solution (60mM) doses induced a contraction. After nicardipine (5.0microM) treatment, pretreating with PTHrP (1-34) (10 7M) showed a 33.5+/-15.5% CCh (0.5microM) increase in induced contractions compared to thr control. CONCLUSIONS: PTHrP (1-34) reduced the spontaneous phasic activity of the smooth muscle strip and caused a concentration-dependent relaxation of the contraction, which induced by carbachol or a high concentration potassium solution. These results support the hypothesis that PTHrP is a regulator of bladder tones. This study results suggested that there is some other mechanism of PTHrP (1-34) on the smooth muscles of the bladder, which is not related to a voltage-sensitive calcium channel.