Beta‐adrenergic stimulation of cyclic AMP production in the rabbit urinary bladder

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Abstract
Although adenyl cyclase stimulation has been associated with beta‐receptor activation in the heart and some smooth muscle systems, it has been shown not to correlate with beta receptor activation in several other smooth muscle preparations. The present study investigates the relationship between cyclic AMP formation and beta‐adrenergic stimulation in the rabbit urinary bladder. The intracellular concentration of cyclic AMP was determined in fresh rabbit bladder and isolated strips incubated under a variety of conditions. The results can be summarized as follows: (1) there was no difference between the cyclic AMP concentration in the bladder base and the bladder body, (2) incubation with theophylline significantly increased the concentration of cyclic AMP in all bladder strips, (3) isoproterenol significantly increased cyclic AMP in the bladder dome but not in the base, and (4) propranolol specifically inhibited the cyclic AMP increase produced by isoproterenol.Incubation with methoxamine, bethanechol, ATP, or diltiazem had no effect on the cyclic AMP concentration. The difference in the response to isoproterenol between bladder base and body correlates very well with both the distribution of beta receptors and the contractile response of these sections to isoproterenol. These studies demonstrate that the bladder body contains an isoproterenol‐sensitive adenyl cyclase system.

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