title: Human coronary arteriolar dilation to adrenomedullin: role of nitric oxide and K(+) channels.
abstract: Adrenomedullin (ADM) is a vasodilator produced by vascular endothelium and smooth muscle cells. Although plasma ADM levels are increased in patients with hypertension, heart failure, and myocardial infarction, little information exists regarding the microvascular response to ADM in the human heart. In the present study we tested the hypothesis that ADM produces coronary arteriolar dilation in humans and examined the mechanism of this dilation. Human coronary arterioles were dissected and cannulated with micropipettes. Internal diameter was measured by video microscopy. In vessels constricted with ACh, the diameter response to cumulative doses of ADM (10(-12)-10(-7) M) was measured in the presence and absence of human ADM-(22-52), calcitonin gene-related peptide-(8-37), N(omega)-nitro-L-arginine methyl ester (L-NAME), indomethacin (Indo), (1)H-[1,2,4]oxadiazolo-[4,3-a]quinoxalin-1-one, SQ-22536, or KCl (60 mM). ADM dilated human coronary arterioles through specific ADM receptors (maximum dilation = 69 +/- 11%). L-NAME or N-monomethyl-L-arginine attenuated dilation to ADM (for L-NAME, maximum dilation = 66 +/- 7 vs. 41 +/- 13%, P < 0.05). Thus the mechanism of ADM-induced dilation involves generation of nitric oxide. However, neither (1)H-[1,2,4]oxadiazolo-[4, 3-a]quinoxalin-1-one, SQ-22536, nor Indo alone altered dilation to ADM. High concentrations of KCl blocked dilation to ADM. The magnitude of ADM dilation was reduced in subjects with hypertension. We propose that, in human coronary arterioles, ADM elicits vasodilation in part through production of nitric oxide and in part through activation of K(+) channels, with little contribution from adenylyl cyclase. The former dilator mechanism is independent of the more traditional pathway involving activation of soluble guanylate cyclase.
authors.affiliation: Cardiovascular Research Center, Medical College of Wisconsin and Zablocki Veterans Administration Medical Center, Milwaukee, Wisconsin 53226, USA.
authors.forename: K
authors.initials: K
authors.lastname: Terata
authors.forename: H
authors.initials: H
authors.lastname: Miura
authors.forename: Y
authors.initials: Y
authors.lastname: Liu
authors.forename: F
authors.initials: F
authors.lastname: Loberiza
authors.forename: D D
authors.initials: DD
authors.lastname: Gutterman
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives* / Q000494:pharmacology; D053607:Adrenomedullin; D000368:Aged; D001160:Arterioles; D015740:Calcitonin Gene-Related Peptide / Q000494:pharmacology; D003326:Coronary Circulation / Q000187:drug effects* / Q000502:physiology*; D003327:Coronary Disease / Q000378:metabolism; D003331:Coronary Vessels / Q000187:drug effects / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D006333:Heart Failure / Q000378:metabolism; D006801:Humans; D006973:Hypertension / Q000378:metabolism; D066298:In Vitro Techniques; D008297:Male; D008833:Microcirculation / Q000187:drug effects / Q000502:physiology; D008875:Middle Aged; D008916:Miotics / Q000494:pharmacology; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000502:physiology*; D010446:Peptide Fragments / Q000494:pharmacology*; D015221:Potassium Channels / Q000502:physiology*; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology; D014665:Vasodilator Agents / Q000494:pharmacology*; D019323:omega-N-Methylarginine / Q000494:pharmacology
chemical_list: D004791:Enzyme Inhibitors; D008916:Miotics; D010446:Peptide Fragments; D015221:Potassium Channels; D014665:Vasodilator Agents; C104782:adrenomedullin (22-52); C058636:calcitonin gene-related peptide (8-37); D053607:Adrenomedullin; C017759:9-(tetrahydro-2-furyl)-adenine; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D000225:Adenine; D015740:Calcitonin Gene-Related Peptide; D019331:NG-Nitroarginine Methyl Ester