alpha,beta-Methylene ATP elicits a reflex pressor response arising from muscle in decerebrate cats.
In part, the exercise pressor reflex is believed to be evoked by chemical stimuli signaling that blood supply to exercising muscles is not adequate to meet its metabolic demands. There is evidence that either ATP or adenosine may function as one of these chemical stimuli. For example, muscle interstitial concentrations of both substances have been found to increase during exercise. This finding led us to test the hypothesis that popliteal arterial injection of alpha,beta-methylene ATP (5, 20, and 50 microg/kg), which stimulates P2X receptors, and 2-chloroadenosine (25 microg/kg), which stimulates P1 receptors, evokes reflex pressor responses in decerebrate, unanesthetized cats. We found that popliteal arterial injection of the two highest doses of alpha,beta-methylene ATP evoked pressor responses, whereas popliteal arterial injection of 2-chloroadenosine did not. In addition, the pressor responses evoked by alpha,beta-methylene ATP were blocked either by section of the sciatic nerve or by prior popliteal arterial injection of pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid (10 mg/kg), a selective P2-receptor antagonist. We conclude that the stimulation of P2 receptors, which are accessible through the vascular supply of skeletal muscle, evokes reflex pressor responses. In addition, our findings are consistent with the hypothesis that the stimulation of P2 receptors comprises part of the metabolic error signal evoking the exercise pressor reflex.
Division of Cardiovascular Medicine, Departments of Internal Medicine and Human Physiology, University of California, Davis, California 95616, USA. rlhanna@ucdavis.edu
Ramy L
RL
Hanna
Shawn G
SG
Hayes
Marc P
MP
Kaufman
D015762:2-Chloroadenosine / Q000008:administration & dosage / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology*; D000818:Animals; D017704:Baroreflex; D001794:Blood Pressure / Q000187:drug effects; D002415:Cats; D003655:Decerebrate State; D003714:Denervation; D006339:Heart Rate / Q000187:drug effects; D007269:Injections, Intra-Arterial; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000502:physiology*; D011150:Popliteal Artery; D058919:Purinergic P2 Receptor Antagonists; D011732:Pyridoxal Phosphate / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D018048:Receptors, Purinergic P2 / Q000187:drug effects / Q000502:physiology; D012119:Respiration / Q000187:drug effects; D012584:Sciatic Nerve / Q000502:physiology
D058919:Purinergic P2 Receptor Antagonists; D018048:Receptors, Purinergic P2; D015762:2-Chloroadenosine; C077792:pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid; D011732:Pyridoxal Phosphate; D000255:Adenosine Triphosphate; C002630:alpha,beta-methyleneadenosine 5'-triphosphate