The effect of sodium based hypo-osmolality on arterial smooth muscle reactivity in vitro

Mutairu Ezimokhai, Nawal Osman

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3 Citations (Scopus)


The study tested the hypothesis that the reduced [Na+](e) and hypo-osmolality of normal pregnancy are causally linked to the attenuation of vascular smooth muscle reactivity in vitro. Aortic rings from nonpregnant female rats were incubated in physiological medium containing 114 mM NaCl/l and the contractile responses to phenylephrine, KCl and CaCl2 as well as the relaxations to acetylcholine and KCl were compared with those of rings incubated in normal medium containing 119 mM NaCl/l. There was no solute substituted for the lowered [Na+]. Experiments with phenylephrine were repeated using de-endothelialized rings and intact rings pretreated with indomethacin. Contractile responses of intact rings (n = 11) in hypo-osmolar solution to phenylephrine were significantly (P < 0.001) lower than of those in normal medium (n = 11). Responses were partially restored by endothelial denudation but not in the presence of indomethacin. Relaxations to acetylcholine (n = 7 for hypo-osmolar; n = 6 for normal solution) and KCl (n = 7 for each of hypo- and normal osmolar) were significantly enhanced (P < 0.05) in rings incubated in hypo-osmolar solution. There was no significant difference between the responses of the rings to KCl, and CaCl2 in either solution. These effects are similar to some of those previously described for vascular smooth muscle in normal pregnancy suggesting that the reduced [Na+](e) and hypo-osmolarity of normal pregnancy may be contributing to the diminished vascular reactivity.

Original languageEnglish
Pages (from-to)269-279
Number of pages11
JournalResearch in Experimental Medicine
Issue number5
Publication statusPublished - Sept 1997
Externally publishedYes


  • Hypo-osmolarity
  • Reduced [Na](e)
  • Vascular reactivity

ASJC Scopus subject areas

  • General Medicine


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