L-arginine-induced conducted signals alter upstream arteriolar responsivity to L-arginine.
Our purpose was to determine whether L-arginine was involved in vascular communication between downstream and upstream locations within a defined microvascular region. Arteriolar diameter was measured for the branches along a transverse arteriole in the superfused cremaster of anesthetized (pentobarbital sodium, 70 mg/kg i.p.) hamsters (N = 53). The upstream branch arterioles dilated significantly to locally applied L-arginine (100 mumol/L pipette concentration) only if the downstream branches (approximately 1400 microns away) were preexposed. With exposure order downstream to upstream, diameter change was last branch, -3.8 +/- 1.5% (of baseline); third, +58.1 +/- 27%; first, +92 +/- 26% (n = 5); with exposure order upstream to downstream: first branch, -0.4 +/- 3%; third, +5 +/- 11%; last, -5.6 +/- 7.5% (n = 4). Thus, downstream preexposure to L-arginine altered the responsivity upstream to locally applied L-arginine. Downstream-applied L-arginine also induced a conducted vasodilation (+17.8 +/- 2.8%; n = 14) 1327 +/- 166 microns upstream. This response was completely blocked by simultaneous sucrose (600 mOsm), halothane (0.0345%), or N omega-nitro-L-arginine (L-NNA, 100 mumol/L) exposure to the feed vessel (second micropipette) midway between the downstream site of L-arginine exposure and the upstream observation site. An acetylcholine-induced conducted vasodilation (+18.1 +/- 2.6%, n = 8) was also completely blocked by sucrose, halothane, or L-NNA.(ABSTRACT TRUNCATED AT 250 WORDS)
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Department of Biophysics, University of Rochester, NY, USA.
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D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001120:Arginine / Q000494:pharmacology*; D001160:Arterioles / Q000187:drug effects* / Q000502:physiology; D006224:Cricetinae; D008297:Male; D008647:Mesocricetus; D018482:Muscle, Skeletal / Q000098:blood supply*; D014664:Vasodilation / Q000187:drug effects*; D014665:Vasodilator Agents / Q000494:pharmacology
D014665:Vasodilator Agents; D001120:Arginine; D000109:Acetylcholine