title: Arteriolar responses to extracellular ATP in striated muscle.
abstract: Blood flow and its distribution must be appropriately regulated to ensure that perfusion is matched to local tissue demands. We investigated the role of ATP in triggering a conducted alteration in arteriolar diameter in the Saran-covered cheek pouch retractor muscle of anesthetized hamsters (n = 60). Vascular responses were observed using in vivo video microscopy upstream from the site of micropressure application of ATP (10(-8)-10(-4) M) either into the lumen or just outside the wall of first- and second-order arterioles. The role of nitric oxide (NO) in the vascular responses to ATP was determined by inhibiting NO synthase activity with N(omega)-nitro-L-arginine methyl ester (L-NAME) with and without coadministration of an excess of L-arginine. Intraluminal application of ATP led to a concentration-dependent vasodilation, which was conducted upstream along the arteriole. The dilatory response was blocked by systemic pretreatment with L-NAME and was maintained in the presence of an excess of L-arginine. In contrast, ATP introduced extraluminally resulted in a conducted vasoconstrictor response that was enhanced by pretreatment with L-NAME. The dilator response to intraluminal ATP, in the context of ATP release from erythrocytes under conditions associated with decreased supply relative to demand, supports a role for the erythrocyte in communicating local tissue needs to the vasculature, enabling the appropriate matching of oxygen supply to demand.
authors.affiliation: Department of Pharmacological and Physiological Science, Saint Louis University Health Services Center, School of Medicine, Missouri 63104, USA.
authors.forename: W T
authors.initials: WT
authors.lastname: McCullough
authors.forename: D M
authors.initials: DM
authors.lastname: Collins
authors.forename: M L
authors.initials: ML
authors.lastname: Ellsworth
mesh_terms: D000241:Adenosine / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D001120:Arginine / Q000494:pharmacology; D001160:Arterioles / Q000187:drug effects / Q000502:physiology*; D002245:Carbon Dioxide / Q000097:blood; D006224:Cricetinae; D006400:Hematocrit; D008297:Male; D008647:Mesocricetus; D018715:Microscopy, Video; D018482:Muscle, Skeletal / Q000098:blood supply*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D010100:Oxygen / Q000097:blood; D010313:Partial Pressure; D012039:Regional Blood Flow; D014664:Vasodilation / Q000187:drug effects
chemical_list: D002245:Carbon Dioxide; D000255:Adenosine Triphosphate; D001120:Arginine; D019001:Nitric Oxide Synthase; D000241:Adenosine; D010100:Oxygen; D019331:NG-Nitroarginine Methyl Ester