E. Brailoiu et al., EFFECTS OF ALPHA-TRINOSITOL ADMINISTERED EXTRACELLULARLY AND INTRACELLULARLY (USING LIPOSOMES) ON RAT AORTA RINGS, European journal of pharmacology, 281(2), 1995, pp. 209-212
The effects of alpha-trinositol, a D-myo-inositol [1,2,6]trisphosphate
derivative, were studied on de-endothelised rat aorta rings. The subs
tance was applied extracellularly as well as intracellularly (by using
liposomes as drug carriers). Upon extracellular administration, the d
rug reduced the level of contraction induced by 40 mM K+ or by phenyle
phrine (10(-5) M). No effects were observed on relaxed preparations. L
iposomes containing alpha-trinositol induced a dose-dependent contract
ion of the preparations under resting tension with a threshold of 10(-
5) M in the aqueous phase. These contractions were heparin-insensitive
but were significantly blocked by D-600 (10(-5) M) (an L-type Ca2+ ch
annel blocker) or in Ca2+-free medium. Our data suggest that alpha-tri
nositol has a plasmalemmal mechanism of action which could involve Ca2
+ influx from the extracellular space.