Increased dilator response to heptanol and octanol in aorta from DOCA-salt-hypertensive rats

This study tests the hypothesis that contractile responses in aortae of hypertensive rats are more dependent on gap junctional communication compared to those from normotensive rats. The experimental approach was pharmacological, using inhibitors of gap junctional activity (heptanol and octanol). Two models of experimental hypertension were characterized: (1) mineralocorticoid (DOCA)-hypertensive rats and (2) stroke-prone spontaneous hypertensive rats (SHRSP). Vessels from DOCA-hypertensive rats showed a greater relaxation to heptanol and octanol, particularly when precontracted with phenylephrine, compared to sham-operated animals. Octanol-induced relaxation in aortic segments from SHRSP did not differ from normotensive values regardless of the agonist used to cause contraction. These results suggest that in DOCA hypertension, gap junctional communication and voltage-operated calcium channels are differentially regulated, which could explain in part the changes in vascular reactivity observed in mineralocorticoid hypertension.