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The crucial role of physiological Ca 2+ concentrations in the production of endothelial nitric oxide and the control of vascular tone
Author(s) -
LopezJaramillo P.,
Gonzalez M.C.,
Palmer R.M.J.,
Moncada S.
Publication year - 1990
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1990.tb12735.x
Subject(s) - nitric oxide , acetylcholine , endothelium , medicine , aorta , extracellular , endocrinology , chemistry , endothelium derived relaxing factor , vasodilation , calcium , blood vessel , nitric oxide synthase , vascular tone , biology , biochemistry
1 The effect of varying the extracellular Ca 2+ concentration on the basal and acetylcholine (ACh)‐induced release of nitric oxide (NO) from the rabbit aorta was investigated by use of a superfusion bioassay system. 2 Changes between 0.5 and 2.0 m m in the concentration of Ca 2+ superfusing the detector bioassay tissues or perfusing endothelium‐denuded donor aortae had no effect on the tone of these tissues. 3 Increasing the concentration of Ca 2+ perfusing endothelium‐containing donor aortae from zero to 1.25 m m caused a transient (24 ± 9 min), concentration‐dependent basal release of NO, which was attenuated at higher concentrations of Ca 2+ (1.5–2.0 m m ). 4 The duration of the effect of Ca 2+ on the basal release of NO was increased by a concomitant infusion of l ‐arginine (100 μ m ) through the donor aorta. 5 Changes in the concentration of Ca 2 + between 0.5 and 2.0 m m had a similar biphasic effect on the release of NO induced by ACh, which was also maximal at 1.25 m m Ca 2+ . 6 When Ca 2+ was removed from the Krebs buffer perfusing the donor aorta, the basal release of NO declined within 2 min. In contrast, the release of NO induced by ACh declined progressively over 60 min. 7 Thus changes in the concentration of Ca 2+ around the physiological range modulate the synthesis of NO by the vascular endothelium and consequently, vascular tone. This may account for the effects of dietary Ca 2+ supplements on the control of some hypertensive states.