Atropine and Micturition Responses by Rats With Intact and Partially Innervated Bladder

Abstract

1 Micturition responses by a group of 17 rats were recorded during a water diuresis. During a 2 h period, uniform volumes of urine were passed at regular intervals; the mean of the voiding responses by each animal was consistent from one water loading period to another. Residual urine volumes were physiologically insignificant. 2 Atropine treatment did not compromise seriously micturition by water-loaded rats. Treated animals micturated more frequently; the mean volume was 68% of control. The residual urine volume was equal to that of controls.3 Several weeks after the surgical removal of half the motor innervation of the bladder, there was no significant effect on micturition. Mean voiding volumes were not different from those of controls; residual urine volumes were the same as before denervation. 4 After half the innervation of the bladder had been destroyed, the effect of atropine on micturition was enhanced. Volumes passed were 50% of control; large residual volumes remained when micturition was over. Only in this group could bladder distension be found. 5 It is concluded that functional responses of the rat urinary bladder are not only resistant to atropine but also to the sizeable reduction in the number of neuroeffector units in the bladder itself. The functional reserve of the rat bladder musculature is remarkably high when assessed by its ability to empty adequately.

Analysis of pressure/flow characteristics in the female rat and their pharmacologic modulation

“…Unlike the situation in conscious rats [Carpenter, 1981;Yaksh et al, 1986;Monkawa et al, 19891, we found that all anesthetized rats had certain amount of fluid retained within the bladder after micturition. Previous studies also reported residual volume [Kruse et al, 1993;Mallory et al, 1989;Maggi et al, 19861.…”

Temporal diabetes- and diuresis-induced remodeling of the urinary bladder in the rat

“…The bladder rapidly adapts to increased urine production by increasing micturition frequency and volume (21). It was reported that an increase in water intake can increase bladder capacity within minutes (1). Such a resetting of the threshold volume for initiating a micturition reflex may involve nervous mechanisms.…”

Micturition in naive and morphine‐dependent rats

“…Elimination was linear during the 2 h required for the water to be excreted (Carpenter, 1981 A mean volume threshold (MV) of 2.5 ± 0.1 ml (s.e.mean) was obtained in a group of 16 rats before the administration of morphine sulphate. In all but one animal the MV of each rat was increased nearly 40% above its own control by morphine sulphate (5 mg kg-') and the group mean was increased to 3.4 ± 0.1 ml.…”

“…It appears likely that morphine, acting upon specific opioid receptors, interferes with these reflex pathways (Dray & Metsch, 1984). To this end it seemed reasonable to examine the action of morphine on micturition of conscious rats; the threshold to induce voiding may be measured repeatedly in rats made to void by water loading (Carpenter, 1981). Moreover, the efficacy of micturition can also be assessed by a determination of the urine volume remaining in the bladder when voiding is completed.…”

“…As voiding occurred the volume passed was recorded on an oscillograph; the transducer which was coupled to a pen-writer by a carrier-wave amplifier, provided a linear chart displacement. Since the transducer output was calibrated, the volume collected in the beaker could be measured directly from the displacement (Carpenter, 1981).…”