Evidence of adenosine 5'-triphosphate release from nerve and P2x-purinoceptor mediated contraction during electrical stimulation of rat urinary bladder smooth muscle.
OBJECTIVE
We provided direct evidence for the existence of purinergic innervation in the rat urinary bladder.


METHODS
The non-adrenergic non-cholinergic (NANC) innervation was studied in 4-month-old Wistar rats. Electric-field stimulation (EFS) of the detrusor muscle strips in the presence of four autonomic blockers (atropine 10(-6) M, guanethidine 10(-6) M, phentolamine 10(-6) M and propranolol 10(-6) M) showed NANC contractions accounted for about 50% of the maximum contractile response. The adenyl purines released from nerves by EFS were detected by HPLC after conversion to ethenopurines. The amount of total purine released was frequency-dependent and could be totally suppressed by tetradotoxin (10(-6) M). The amount of ATP released was significantly greater than those for ADP, AMP and adenosine (p < 0.05, n = 4). Desensitization induced by alpha, beta-MeATP (10(-6) to 10(-4) M), a P2x receptor agonist, reduced the NANC contraction. In addition, the NANC contraction was also abolished by P2 receptor blocker suramin (10(-4) to 10(-3) M) and P2x receptor blocker PPADS (10(-5) to 10(-4) M.).


CONCLUSIONS
The results of the present study give evidence to support purinergic nerve-mediated bladder smooth muscle contractions in the rat. Among the purine nucleotides, ATP is the dominant purinergic neurotransmitter released and P2x receptor activation is responsible for the NANC contractile response.
Tong
Y C
YC
Department of Urology, National Cheng Kung University Medical College, Tainan, Taiwan, Republic of China.
Hung
Y C
YC
Shinozuka
K
K
Kunitomo
M
M
Cheng
J T
JT
D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000378:metabolism* / Q000494:pharmacology; D000818:Animals; D004558:Electric Stimulation; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology*; D009130:Muscle, Smooth / Q000187:drug effects / Q000294:innervation / Q000378:metabolism* / Q000502:physiology*; D018377:Neurotransmitter Agents / Q000502:physiology; D011732:Pyridoxal Phosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D018048:Receptors, Purinergic P2 / Q000187:drug effects / Q000502:physiology*; D013498:Suramin / Q000494:pharmacology; D013779:Tetrodotoxin / Q000494:pharmacology; D001743:Urinary Bladder / Q000187:drug effects / Q000294:innervation / Q000378:metabolism* / Q000502:physiology*
D018377:Neurotransmitter Agents; D018048:Receptors, Purinergic P2; C077792:pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid; D013779:Tetrodotoxin; D011732:Pyridoxal Phosphate; D013498:Suramin; D000255:Adenosine Triphosphate; C002630:alpha,beta-methyleneadenosine 5'-triphosphate