What is the function of A1 (adrenergic) receptors in urinary storage?

The function of A1 (adrenergic) receptors in urinary storage is primarily associated with facilitating internal urethral sphincter contraction. When A1 receptors are activated, they promote contraction of the smooth muscle within the internal urethral sphincter, which helps to maintain urinary retention by preventing urine from leaking from the bladder into the urethra. This is crucial during the storage phase of micturition, as it supports the bladder's capacity to store urine without involuntary release.

In terms of bladder function during this phase, the contraction of the internal urethral sphincter, mediated by A1 receptors, helps create a closure mechanism that prevents the escape of urine. This contributes significantly to the overall control of urinary storage, as it allows the bladder to fill without involuntary voiding.

The other aspects of micturition, such as detrusor muscle contraction or external urethral sphincter relaxation, are governed by different mechanisms. Detrusor muscle relaxation during storage is primarily due to beta-adrenergic receptor activity, while external urethral sphincter control involves somatic nervous system pathways, further distinguishing the specific role of A1 receptors during urinary storage.