Effect of Age on Cholinergic Muscarinic Responsiveness and Receptors in the Rat Urinary Bladder

Abstract

The effects of age on urinary bladder responsiveness to muscarinic agonists and on the Bmax and Kd of the binding of [3H]quinuclidinyl benzilate (QNB) to muscarinic receptors of the bladder were studied. Bladder bodies and bases were isolated from Fischer 344 rats, ages seven, 16 and 27 months. No age-dependent change in maximum KCl-elicited isotonic contractions was observed in either bladder region. The bladder base showed an age-dependent increase in the maximum contractions (Emax) elicited by muscarinic agonists. The Emax values for bladder bases from rats 27 months of age were 44 per cent, 58 per cent and 76 per cent greater than those from rats seven months of age for acetylcholine, bethanechol and oxotremorine, respectively. No such alteration in responsiveness was observed in the bladder body with age. There were no age-related changes in ED50 values for the three agonists in either bladder region. Analysis of [3H]QNB binding in the bladder base demonstrated a modest 18 per cent increase in the Bmax (fmol./mg. tissue) from seven to 16 months and a significant 39 per cent decrease from 16 to 27 months. In the bladder body, the Bmax progressively increased by 25 per cent from seven to 27 months. The Kd values of [3H]QNB did not change with age in either region. The data demonstrate that the age-related increase in the responsiveness of the bladder is regionally specific and cannot be explained by a change in the number or affinity of muscarinic receptors.

Selective changes in the <i>α</i>-adrenoceptor-mediated contraction in the senescent rat urinary bladder

“…These results indicate that bladder contraction via voltage-dependent Ca 2+ channel was not affected in aged rat. In accordance with the present study, it is reported that KCl-induced isotonic contraction was not altered by aging [7,9]. …”

“…Several reports indicated that both alpha-adrenergic receptor and muscarinic receptor existed not only in bladder body but also in trigone [6][7][8]. However, there are no confidential results whether α-adrenergic as well as muscarinic receptors play a role in age-related functional changes of urinary bladder.…”

Potentiation of β-Adrenergic Function by Saiboku-To and Bakumondo-To in Canine Bronchial Smooth Muscle

“…Surprisingly, there have been only a few reports that age affects mus carinic cholinergic receptors in the rat prostate. Three reports (29)(30)(31) have examined muscarinic receptors in the aging rat urinary bladder. Two showed an increase (29,30) in the density of receptors, while the other showed no change (31).…”

“…Three reports (29)(30)(31) have examined muscarinic receptors in the aging rat urinary bladder. Two showed an increase (29,30) in the density of receptors, while the other showed no change (31). However, these discrepancies might be explained by possible differences in the nature of the tissue samples and/or rat strain.…”

Effects of long-term estradiol treatment on the contractile response to muscarine and muscarinic receptor subtypes in the bladder of aged female rats

“…There is a heterogeneous population of muscarinic receptor subtypes in many tissues, including the urinary bladder. A predominance of the M 2 receptor subtype along with a smaller population of M 3 receptors has been observed in the urinary bladder smooth muscle (15). Although both receptors influence contraction of the detrusor muscle, the M 3 receptor appears to be the most functionally important, as it mediates direct contraction of the detrusor muscle (4).…”