TY - JOUR
T1 - Mechanisms of acetylcholine-mediated vasodilation in systemic arteries from mourning doves (Zenaida macroura)
AU - Jarrett, Catherine
AU - Lekic, Mateja
AU - Smith, Christina L.
AU - Pusec, Carolina M.
AU - Sweazea, Karen
N1 - Funding Information:
Acknowledgments The authors thank Dr. Benjimen R. Walker for providing constructive criticism of the manuscript. This study was supported by new faculty start-up funds (K.L.S.) as well as funds provided to C.J. from the ASU Graduate and Professional Student Association in addition to the ASU Chapter of Sigma Xi, The Scientific Research Society.
PY - 2013/10
Y1 - 2013/10
N2 - For mammals, acetylcholine (ACh) promotes endothelium-dependent vasodilation primarily through nitric oxide (NO) and prostaglandin-mediated pathways, with varying reliance on endothelial-derived hyperpolarizing factors. Currently, no studies have been conducted on small systemic arteries from wild birds. We hypothesized that ACh-mediated vasodilation of isolated small arteries from mourning doves (Zenaida macroura) would likewise depend on endothelial-derived factors. Small resistance mesenteric and cranial tibial (c. tibial) arteries (80-150 μm, inner diameter) were cannulated and pre-constricted to 50 % of resting inner diameter with phenylephrine then exposed to increasing concentrations of ACh (10-9-10-5 M) or the NO donor, sodium nitroprusside (SNP; 10-12-10-3 M). For mesenteric arteries, ACh-mediated vasodilation was significantly blunted with the potassium channel antagonist tetraethylammonium chloride (TEA, 10 mM); whereas responses were only moderately impaired with endothelial disruption or inhibition of prostaglandins (indomethacin, 10 μM). In contrast, endothelial disruption as well as exposure to TEA largely abolished vasodilatory responses to ACh in c. tibial arteries while no effect of prostaglandin inhibition was observed. For both vascular beds, responses to ACh were moderately dependent on the NO signaling pathway. Inhibition of NO synthase had no impact, despite complete reversal of phenylephrine-mediated tone with SNP, whereas inhibition of soluble guanylate cyclase (sGC) caused minor impairments. Endothelium-independent vasodilation also relied on potassium channels. In summary, ACh-mediated vasodilation of mesenteric and c. tibial arteries occurs through the activation of potassium channels to induce hyperpolarization with moderate reliance on sGC. Prostaglandins likewise play a small role in the vasodilatory response to ACh in mesenteric arteries.
AB - For mammals, acetylcholine (ACh) promotes endothelium-dependent vasodilation primarily through nitric oxide (NO) and prostaglandin-mediated pathways, with varying reliance on endothelial-derived hyperpolarizing factors. Currently, no studies have been conducted on small systemic arteries from wild birds. We hypothesized that ACh-mediated vasodilation of isolated small arteries from mourning doves (Zenaida macroura) would likewise depend on endothelial-derived factors. Small resistance mesenteric and cranial tibial (c. tibial) arteries (80-150 μm, inner diameter) were cannulated and pre-constricted to 50 % of resting inner diameter with phenylephrine then exposed to increasing concentrations of ACh (10-9-10-5 M) or the NO donor, sodium nitroprusside (SNP; 10-12-10-3 M). For mesenteric arteries, ACh-mediated vasodilation was significantly blunted with the potassium channel antagonist tetraethylammonium chloride (TEA, 10 mM); whereas responses were only moderately impaired with endothelial disruption or inhibition of prostaglandins (indomethacin, 10 μM). In contrast, endothelial disruption as well as exposure to TEA largely abolished vasodilatory responses to ACh in c. tibial arteries while no effect of prostaglandin inhibition was observed. For both vascular beds, responses to ACh were moderately dependent on the NO signaling pathway. Inhibition of NO synthase had no impact, despite complete reversal of phenylephrine-mediated tone with SNP, whereas inhibition of soluble guanylate cyclase (sGC) caused minor impairments. Endothelium-independent vasodilation also relied on potassium channels. In summary, ACh-mediated vasodilation of mesenteric and c. tibial arteries occurs through the activation of potassium channels to induce hyperpolarization with moderate reliance on sGC. Prostaglandins likewise play a small role in the vasodilatory response to ACh in mesenteric arteries.
KW - Acetylcholine
KW - Artery
KW - Avian
KW - Potassium
KW - Vasodilation
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U2 - 10.1007/s00360-013-0757-0
DO - 10.1007/s00360-013-0757-0
M3 - Article
C2 - 23640140
AN - SCOPUS:84884511758
SN - 0174-1578
VL - 183
SP - 959
EP - 967
JO - Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology
JF - Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology
IS - 7
ER -