title: ATP overflow in skeletal muscle 1A arterioles.
abstract: The purpose of this study was to investigate the sources of ATP in the 1A arteriole, and to investigate age-related changes in ATP overflow. Arterioles (1A) from the red portion of the gastrocnemius muscle were isolated, cannulated and pressurized in a microvessel chamber with field stimulation electrodes. ATP overflow was determined using probes specific for ATP and null probes that were constructed similar to the ATP probes, but did not contain the enzyme coating. ATP concentrations were determined using a normal curve (0.78 to 25 micromol l(-1) ATP). ATP overflow occurred in two phases. Phase one began in the first 20 s following stimulation and phase two started 35 s after field stimulation. Tetrodotoxin, a potent neurotoxin that blocks action potential generation in nerves, abolished both phases of ATP overflow. alpha1-Receptor blockade resulted in a small decrease in ATP overflow in phase two, but endothelial removal resulted in an increase in ATP overflow. ATP overflow was lowest in 6-month-old rats and highest in 12- and 2-month-old rats (P<0.05). ATP overflow measured via biosensors was of neural origin with a small contribution from the vascular smooth muscle. The endothelium seems to play an important role in attenuating ATP overflow in 1A arterioles.
authors.affiliation: Department of Health Science, Kinesiology, Recreation and Dance, 308V HPER Building, 1 University of Arkansas, Fayetteville, AR 72701, USA. hkluess@uark.edu
authors.forename: Heidi A
authors.initials: HA
authors.lastname: Kluess
authors.forename: Audrey J
authors.initials: AJ
authors.lastname: Stone
authors.forename: Kirk W
authors.initials: KW
authors.lastname: Evanson
mesh_terms: D000200:Action Potentials; D000255:Adenosine Triphosphate / Q000378:metabolism*; D058646:Adrenergic alpha-1 Receptor Agonists / Q000494:pharmacology; D058668:Adrenergic alpha-1 Receptor Antagonists / Q000494:pharmacology; D000367:Age Factors; D000375:Aging; D000779:Anesthetics, Local / Q000494:pharmacology; D000818:Animals; D001160:Arterioles / Q000294:innervation / Q000378:metabolism; D015374:Biosensing Techniques; D004558:Electric Stimulation; D004730:Endothelium, Vascular / Q000378:metabolism; D066298:In Vitro Techniques; D018482:Muscle, Skeletal / Q000098:blood supply*; D009131:Muscle, Smooth, Vascular / Q000294:innervation* / Q000378:metabolism; D010656:Phenylephrine / Q000494:pharmacology; D011224:Prazosin / Q000494:pharmacology; D051381:Rats; D011916:Rats, Inbred F344; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000378:metabolism*; D013779:Tetrodotoxin / Q000494:pharmacology
chemical_list: D058646:Adrenergic alpha-1 Receptor Agonists; D058668:Adrenergic alpha-1 Receptor Antagonists; D000779:Anesthetics, Local; D010656:Phenylephrine; D013779:Tetrodotoxin; D000255:Adenosine Triphosphate; D011224:Prazosin