Tropical
Journal of Pharmaceutical Research, June 2009; 8(3):
209-214
Abstract
Purpose:
The use of L-arginine and potassium chloride separately
as supplements has been reported to result in altered
vascular reactivity. The concentration of either agent
used has varied widely and there has been no report on
the outcome of combined supplementation with both agents
on vascular reactivity. We therefore designed this study
to measure thoracic aortic ring reactivity after
five-week co-supplementation with 1% L-arginine and
0.75% potassium chloride.
Methods:
Endothelium-intact and endothelium-denuded aortic rings
obtained from Sprague-Dawley rats which received the
combined supplements were subjected to graded
concentrations of carbachol or noradrenaline in organ
baths. The maximum responses (Emax) and the
negative logarithm of the concentration producing 50% of
maximum responses (pD2) were computed
as indices of vasoreactivity.
Results:
Co-supplementation significantly enhanced the relaxant
effects of carbachol irrespective of the status of the
endothelium although relaxation was by far higher in
endothelium-intact rings. In concentration-response
curves obtained with noradrenaline, Emax
and pD2 values were significantly (P
< 0.05) reduced in endothelium-intact rings obtained
from rats which received the supplements. In
endothelium-denuded rings, responses to noradrenaline
were not significantly different from those of control.
Conclusion:
Co-supplementation with the agents enhances the relaxant
effect of carbachol independent of the status of the
endothelium while attenuating responses to noradrenaline
in endothelium-dependent manner. This suggests that oral
L-arginine and potassium co-supplementation may possess
beneficial vascular effects.
Keywords:
Potassium chloride, L-arginine,
co-supplementation, aortic rings
