This study tests the hypothesis that contractile responses in aortae of hyp
ertensive rats are more dependent on gap junctional communication compared
to those from normotensive rats. The experimental approach was pharmacologi
cal, using inhibitors of gap junctional activity (heptanol and octanol). Tw
o models of experimental hypertension were characterized: (1) mineralocorti
coid (DOCA)-hypertensive rats and (2) stroke-prone spontaneous hypertensive
rats (SHRSP), Vessels from DOCA-hypertensive rats showed a greater relaxat
ion to heptanol and octanol, particularly when precontracted with phenyleph
rine, compared to sham-operated animals. Octanol-induced relaxation in aort
ic segments from SHRSP did not differ from normotensive values regardless o
f the agonist used to cause contraction, These results suggest that in DOCA
hypertension, gap junctional communication and voltage-operated calcium ch
annels are differentially regulated, which could explain in part the change
s in vascular reactivity observed in mineralocorticoid hypertension. Copyri
ght (C) 2001 S. Karger AG, Basel.