Comparative effects of magnesium salts on reactivity of arterioles and venules to constrictor agents: an in situ study on microcirculation.
The influence of different magnesium salts (i.e., MgCl2, MgSO4, Mg aspartate HCl and Mg acetate) on reactivity of rat mesenteric arterioles (10-25 micron I.D.) and venules (15-30 micron I.D.) to standard constrictor doses of epinephrine and BaCl2 was examined utilizing perivascular, i.a. and i.v. administration of each Mg salt. Perivascular application (0.1, 1.0 and 10 mumol) of the four Mg salts on the microvessels attenuated the vasoconstrictor actions of both epinephrine and BaCl2, dose-dependently. With respect to arterioles, the vasoconstriction induced by BaCl2 was inhibited more potently by each Mg salt than that induced by epinephrine; the reverse was observed with respect to the venules. MgCl2 displayed the most potent antagonism to the constriction induced by BaCl2 in arterioles as well as by epinephrine in venules. Infusion of each Mg salt in very low doses (e.g., 0.1 mumol/min i.a.) resulted in significant attenuation of the arteriolar constrictions induced by both stimulants. However, the difference in the degree of attenuation on i.a. infusion of each Mg salt was significantly less than that observed by perivascular pretreatment. Arteriolar constrictions induced by epinephrine and BaCl2 were also attenuated by systemic i.v. infusion of each Mg salt, except for MgSO4, when low doses (e.g., 0.1 and 1.0 mumol/min.) were given; surprisingly, high dose i.v. infusion (10 and 20 mumol/min) often potentiated arteriolar constrictions induced by both stimulants, but the magnitude of this potentiation depended on the Mg salt utilized.(ABSTRACT TRUNCATED AT 250 WORDS)
Nishio
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A
Department of Physiology, State University of New York Health Science Center, Brooklyn.
Gebrewold
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A
Altura
B T
BT
Altura
B M
BM
D000085:Acetates / Q000494:pharmacology; D019342:Acetic Acid; D000818:Animals; D001160:Arterioles / Q000187:drug effects; D001224:Aspartic Acid / Q000494:pharmacology; D001464:Barium / Q000494:pharmacology; D017609:Barium Compounds; D002712:Chlorides; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004837:Epinephrine / Q000494:pharmacology; D008274:Magnesium / Q000494:pharmacology*; D015636:Magnesium Chloride; D008278:Magnesium Sulfate / Q000494:pharmacology; D008297:Male; D008833:Microcirculation / Q000187:drug effects; D051381:Rats; D011919:Rats, Inbred Strains; D013152:Splanchnic Circulation / Q000187:drug effects*; D014661:Vasoconstriction / Q000187:drug effects; D014662:Vasoconstrictor Agents / Q000494:pharmacology*; D014699:Venules / Q000187:drug effects
D000085:Acetates; D017609:Barium Compounds; D002712:Chlorides; D014662:Vasoconstrictor Agents; D015636:Magnesium Chloride; C024986:barium chloride; D001464:Barium; D001224:Aspartic Acid; D008278:Magnesium Sulfate; D008274:Magnesium; D019342:Acetic Acid; D004837:Epinephrine