TY - JOUR
T1 - Vasoactive effects of methylamine in isolated human blood vessels
T2 - Role of semicarbazide-sensitive amine oxidase, formaldehyde, and hydrogen peroxide
AU - Conklin, D. J.
AU - Cowley, H. R.
AU - Wiechmann, R. J.
AU - Johnson, G. H.
AU - Trent, M. B.
AU - Boor, P. J.
PY - 2004/2
Y1 - 2004/2
N2 - It is hypothesized that methylamine (MA) and semicarbazide-sensitive amine oxidase (SSAO) activity are involved in the cardiovascular complications in human diabetics. To test this, we 1) determined the acute vasoactive effects of MA (1-1,000 μmol/1) in uncontracted and norepinephrine (NE; 1 μmol/1)-precontracted human blood vessels used for coronary artery bypass grafts [left internal mammary artery (LIMA), radial artery (RA), and right saphenous vein (RSV)]; 2) tested whether MA effects in LIMA and RSV were dependent on SSAO activity using the SSAO inhibitor semicarbazide (1 mmol/l, 15 min); 3) determined the effects of MA metabolites formaldehyde and hydrogen peroxide in LIMA and RSV; 4) tested whether the MA response was nitric oxide, prostaglandin, or hyperpolarization dependent; 5) measured the LIMA and RSV cGMP levels after MA exposure; and 6) quantified SSAO activity in LIMA, RA, and RSV. In NE-precontracted vessels, MA stimulated a biphasic response in RA and RSV (rapid contraction followed by prolonged relaxation) and dominant relaxation in LIMA (mean ± SE, %relaxation: 55.4 ± 3.9, n = 30). The MA-induced relaxation in LIMA was repeatable, nontoxic, and age independent. Semicarbazide significantly blocked MA-induced relaxation (%inhibition: 82.5 ± 4.8, n = 7) and SSAO activity (%inhibition: 98.1 ± 1.3, n = 26) in LIMA. Formaldehyde (%relaxation: 37.3 ± 18.6, n = 3) and H 2O2 (%relaxation: 55.6 ± 9.0, n = 9) at 1 mmol/l relaxed NE-precontracted LIMA comparable with MA. MA-induced relaxation in LIMA was nitric oxide, prostaglandin, and possibly cGMP independent and blocked by hyperpolarization. We conclude that vascular SSAO activity may convert endogenous amines, like MA, to vasoactive metabolites.
AB - It is hypothesized that methylamine (MA) and semicarbazide-sensitive amine oxidase (SSAO) activity are involved in the cardiovascular complications in human diabetics. To test this, we 1) determined the acute vasoactive effects of MA (1-1,000 μmol/1) in uncontracted and norepinephrine (NE; 1 μmol/1)-precontracted human blood vessels used for coronary artery bypass grafts [left internal mammary artery (LIMA), radial artery (RA), and right saphenous vein (RSV)]; 2) tested whether MA effects in LIMA and RSV were dependent on SSAO activity using the SSAO inhibitor semicarbazide (1 mmol/l, 15 min); 3) determined the effects of MA metabolites formaldehyde and hydrogen peroxide in LIMA and RSV; 4) tested whether the MA response was nitric oxide, prostaglandin, or hyperpolarization dependent; 5) measured the LIMA and RSV cGMP levels after MA exposure; and 6) quantified SSAO activity in LIMA, RA, and RSV. In NE-precontracted vessels, MA stimulated a biphasic response in RA and RSV (rapid contraction followed by prolonged relaxation) and dominant relaxation in LIMA (mean ± SE, %relaxation: 55.4 ± 3.9, n = 30). The MA-induced relaxation in LIMA was repeatable, nontoxic, and age independent. Semicarbazide significantly blocked MA-induced relaxation (%inhibition: 82.5 ± 4.8, n = 7) and SSAO activity (%inhibition: 98.1 ± 1.3, n = 26) in LIMA. Formaldehyde (%relaxation: 37.3 ± 18.6, n = 3) and H 2O2 (%relaxation: 55.6 ± 9.0, n = 9) at 1 mmol/l relaxed NE-precontracted LIMA comparable with MA. MA-induced relaxation in LIMA was nitric oxide, prostaglandin, and possibly cGMP independent and blocked by hyperpolarization. We conclude that vascular SSAO activity may convert endogenous amines, like MA, to vasoactive metabolites.
KW - Amine metabolism
KW - Coronary artery bypass grafts
KW - Diabetes
KW - HO
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U2 - 10.1152/ajpheart.00690.2003
DO - 10.1152/ajpheart.00690.2003
M3 - Article
C2 - 14715500
AN - SCOPUS:0942276495
SN - 0363-6135
VL - 286
SP - H667-H676
JO - American Journal of Physiology - Heart and Circulatory Physiology
JF - American Journal of Physiology - Heart and Circulatory Physiology
IS - 2 55-2
ER -