Alanine increases blood pressure during hypotension

摘要

Many amino acids reportedly alter cardiovascular function when administered parenterally. The most studied such compound has been tyrosine, which increases blood pressure (BP) during hemorrhagic shock, and decreases BP in spontaneously hypertensive rats (SHR's). Tryptophan similarly reduces BP in SHR's; glycine increases cardiac output and decreases mean arterial pressure in dogs; and methionine reduces the contractile responses of the rat's aorta to potassium chloride. Butta & Adler-Graschinsky (1987) recently reported that low concentrations of L-alanine diminished norepinephrine release from the cardiac sympathetic nerves in isolated rat atria. In contrast, higher concentrations of the amino acid increased the contractile responses to exogenous norepinephrine, suggesting that L-alanine might also act in vivo to modulate cardiovascular responses to circulating catecholamines. Catecholamines mediate compensatory responses to hemorrhage, and since their physiologic effects could potentially be altered by L-alanine, the amino acid's effects on BP during hemorrhagic shock was examined.