A tachykinin-mediated component in the atropine-resistant contractile response of the rat urinary bladder to nerve stimulation

The effects of human and porcine neuropeptide Y (NPY) on electrically induced contractions of smooth muscle strips from rat urinary bladder, urethra, and vas deferens were investigated. NPY (10 nM-10 microM) inhibited to the contractile response in all preparations. The magnitude of inhibition by NPY was dependent on frequency of stimulation in each organ, the inhibition being in general much greater (80-100%) at low frequencies (2-5 Hz) than at high frequencies (30-40% at 10-100 Hz). The vas deferens and urethra exhibited nearly maximal inhibition (90-100%) over a broader range of stimulus frequencies (1-20 Hz), while the bladder exhibited a more prominent inhibition at frequencies of stimulation below 2 Hz. When tested at 20 Hz stimulation the urethra and vas deferens were very sensitive (70-90% inhibition) to both types of NPY, whereas bladder strips were much less sensitive to NPY and the effect differed with the two types of NPY (16% inhibition with human NPY and 39% inhibition with porcine NPY). In the urinary bladder, NPY inhibited the cholinergic component of the contractile response, while in the urethra adrenergic transmission was primarily affected. These studies suggest that NPY, which is present in both cholinergic and adrenergic neurons in the pelvic ganglia, may have an important role in the neural control of the lower urinary tract by participating in autoinhibition at autonomic nerve terminals as well as in the heterosynaptic interactions between the cholinergic and adrenergic pathways.

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The effects of nucleotides on the response of the isolated guinea pig urinary bladder to nonadrenergic, noncholinergic nerve stimulation

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y81-187 ◽

1981 ◽

Vol 59 (11) ◽

pp. 1199-1201 ◽

Cited By ~ 12

Author(s):

P. Lukacsko ◽

R. D. Krell

Keyword(s):

Electrical Stimulation ◽

Urinary Bladder ◽

Guinea Pig ◽

Nerve Stimulation ◽

Purinergic Receptors ◽

Contractile Response ◽

Krebs Solution ◽

Metabolic Products ◽

Per Se ◽

Intramural Nerve

The ability of adenosine 5′-triphosphate (ATP) to suppress the contractile response of guinea pig urinary bladder to nonadrenergic, noncholinergic nerve stimulation was investigated. Strips of guinea pig urinary bladder were incubated for 1 h at 37 °C in a modified Krebs solution containing atropine (2 × 10−7 M), guanethidine (1 × 10−6 M), and indomethacin (5.5 × 10−6 M). Four successive administrations of ATP, guanosine 5′-triphosphate (GTP), or cytidine 5′-triphosphate (CTP), each at 5 × 10−4 M, in the absence of washout resulted in complete desensitization of the tissue to the contractile effect of the nucleotide. Strips desensitized to GTP or CTP were also nonresponsive to ATP. The response of the strips to electrical stimulation (100 V, 0.1-ms pulse, 5-s train at 3 Hz) was markedly reduced following desensitization with ATP but only slightly with GTP or CTP. Under similar conditions, adenosine 5′-monophosphate (AMP) or diphosphate (ADP) or adenosine (A) also reduced the response of the strips to intramural nerve stimulation, but guanosine.5′-monophosphate (GMP) or diphosphate (GDP), guanosine (G), cytidine 5′-monophosphate (CMP) or diphosphate (CDP), or cytidine (C) did not. The present data suggest that desensitization of smooth muscle to exogenous ATP may be predominantly the result of its conversion to metabolic products rather than inactivation of "purinergic" receptors per se.

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