An electrophysiological study of excitatory purinergic neuromuscular transmission in longitudinal smooth muscle of chicken anterior mesenteric artery.
1. The object of the present study was to clarify the neurotransmitters controlling membrane responses to electrical field stimulation (EFS) in the longitudinal smooth muscle cells of the chicken anterior mesenteric artery. 2. EFS (5 pulses at 20 Hz) evoked a depolarization of amplitude 19.7+/-2.1 mV, total duration 29.6+/-3.1 s and latency 413.0+/-67.8 ms. This depolarization was tetrodotoxin (TTX)-sensitive and its amplitude was partially decreased by atropine (0.5 microM); however, its duration was shortened by further addition of prazosin (10 microM). 3. Atropine/prazosin-resistant component was blocked by the nonspecific purinergic antagonist, suramin, in a dose-dependent manner, indicating that this component is mediated by the neurotransmitter adenosine 5'-triphosphate (ATP). 4. Neither desensitization nor blocking of P2X receptor with its putative receptor agonist alpha,beta-methylene ATP (alpha,beta-MeATP, 1 microM) and its antagonist pyridoxalphosphate-6-azophenyl-2',4'-disulfonic (PPADS, up to 50 microM), had significant effect on the purinergic depolarization. In contrast, either desensitization or blocking of P2Y receptor with its putative agonist 2-methylthioATP (2-MeSATP, 1 microM) and its antagonist Cibacron blue F3GA (CBF3GA, 10 microM) abolished the purinergic depolarization, indicating that this response is mediated through P2Y but not P2X receptor. 5. The purinergic depolarization was inhibited by pertussis toxin (PTX, 600 ng ml(-1)). Furthermore, it was significantly inhibited by a phospholipase C (PLC) inhibitor, U-73122 (10 microM), indicating that the receptors involved in mediating the purinergic depolarization are linked to a PTX-sensitive G-protein, which is involved in a PLC-mediated signaling pathway. 6. Data of the present study suggest that the EFS-induced excitatory membrane response occurring in the longitudinal smooth muscle of the chicken anterior mesenteric artery is mainly purinergic in nature and is mediated via P2Y purinoceptors.
Khalifa
Maisa
M
Department of Basic Veterinary Science, Laboratory of Physiology, The United Graduate School, Gifu University, 1-1 Yanagido, Gifu, 501-1193, Japan.
El-Mahmoudy
AbuBakr
A
Shiina
Takahiko
T
Shimizu
Yasutake
Y
Nikami
Hideki
H
El-Sayed
Mossad
M
Kobayashi
Haruo
H
Takewaki
Tadashi
T
D000255:Adenosine Triphosphate / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors / Q000494:pharmacology; D000818:Animals; D002645:Chickens; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D004594:Electrophysiology; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D008638:Mesenteric Arteries / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D008839:Microelectrodes; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology*; D018377:Neurotransmitter Agents / Q000037:antagonists & inhibitors / Q000494:pharmacology; D010477:Perfusion; D037342:Pertussis Toxin / Q000494:pharmacology; D058913:Purinergic Agonists; D058914:Purinergic Antagonists; D058910:Purinergic P2 Receptor Agonists; D058919:Purinergic P2 Receptor Antagonists; D011983:Receptors, Purinergic / Q000187:drug effects / Q000502:physiology*; D018048:Receptors, Purinergic P2 / Q000187:drug effects / Q000502:physiology; D015398:Signal Transduction; D013498:Suramin / Q000494:pharmacology; D013873:Thionucleotides / Q000494:pharmacology; D014227:Triazines / Q000494:pharmacology; D010738:Type C Phospholipases / Q000494:pharmacology
D018377:Neurotransmitter Agents; D058913:Purinergic Agonists; D058914:Purinergic Antagonists; D058910:Purinergic P2 Receptor Agonists; D058919:Purinergic P2 Receptor Antagonists; D011983:Receptors, Purinergic; D018048:Receptors, Purinergic P2; D013873:Thionucleotides; D014227:Triazines; C012842:Cibacron Blue F 3GA; D013498:Suramin; D000255:Adenosine Triphosphate; D037342:Pertussis Toxin; D010738:Type C Phospholipases; C008501:2-methylthio-ATP