Details

Autor(en) / Beteiligte

• Tolsa, Jean-Francois
• Gao, Yuansheng
• Raj, J. Usha

Titel

Developmental change in magnesium sulfate-induced relaxation of rabbit pulmonary arteries

Ist Teil von

• Journal of applied physiology (1985), 1999-11, Vol.87 (5), p.1589-1594

Ort / Verlag

Bethesda, MD: Am Physiological Soc

Erscheinungsjahr

1999

Quelle

MEDLINE

Beschreibungen/Notizen

• Department of Pediatrics, Harbor-UCLA Medical Center, University of California, Los Angeles, School of Medicine, Torrance, California 90502 Magnesium causes a variety of vascular smooth muscle to relax. The present study was designed to determine whether there is a developmental change in the magnesium-induced response of pulmonary vasculature. Isolated pulmonary arteries (PA) of newborn (1- to 3-day-old) and juvenile (4- to 6-wk-old) rabbits were suspended in organ chambers filled with modified Krebs-Ringer bicarbonate solution (95% O 2 -5% CO 2 , 37.0°C), and their isometric tension was recorded. In arteries preconstricted with endothelin-1 to a similar tension level, MgSO 4 caused greater relaxation of juvenile rabbit PA than that of the newborn rabbit PA. Verapamil, a voltage-dependent Ca 2+ channel blocker, attenuated magnesium-induced relaxation in juvenile rabbit PA but not in newborn PA. The uptake of Ca 2+ of juvenile rabbit PA was inhibited by MgSO 4 , and the inhibition was attenuated by verapamil. The uptake of Ca 2+ of newborn rabbit PA was smaller than that of the juvenile PA and was not significantly affected by MgSO 4 and verapamil. These results demonstrate that there is a developmental increase in the dilator effect of MgSO 4 in rabbit PA. In newborn rabbit PA, an incomplete maturation of the voltage-dependent Ca 2+ channels may contribute to the smaller vasodilation induced by MgSO 4 . perinatal pulmonary circulation; verapamil; voltage-dependent calcium channels; vasorelaxation