Levcromakalim decreases vascular tone, cytoplasmic Ca2+ and Ca2+ sensitivity in canine basilar artery

The vascular effect of glibenclamide: A systematic review

Objective:

To systematically review the vascular effects of glibenclamide.

Background:

Infusion of adenosine triphosphate (ATP)-sensitive potassium (KATP) channel opener (KCO) levcromakalim dilates cranial arteries and induces headache and migraine attacks. Recent data show that levcromakalim-induced vasodilation is associated with headache. Glibenclamide is a KATP channel blocker that may alter the vascular tone and thus has an impact on headache or migraine prevention.

Methods:

A search through PubMed was undertaken for studies investigating the vascular effects of glibenclamide in vitro as well as in vivo published until July 2019.

Results:

We identified 58 articles; 31 in vitro studies, 24 in vivo studies and 3 studies with both. The main findings were that glibenclamide inhibited levcromakalim-induced and other KCOs-induced vasodilation, while the basal vascular tone remained unchanged.

Conclusion:

Glibenclamide could inhibit vasodilation by KCOs, and further studies are needed to clarify the vascular effect of glibenclamide on human cranial arteries.

Contractile responses of the human umbilical artery to KCl and serotonin in Ca-free medium and the effects of levcromakalim

It is known that K(ATP) channel openers inhibit the release and refilling of Ca(2+) from intracellular stores. The present study was designed to test the effects of levcromakalim in human umbilical artery (HUA) rings stimulated by serotonin (5-HT) and KCl in Ca-free medium. Umbilical cords were obtained at vaginal or cesarean deliveries from healthy, term pregnancies. After the isolation, HUA rings were placed in organ baths in solution with indomethacin (10(-5) M) and N(G)-nitro-L-arginine methyl ester (L-NAME) (10(-3) M) at 37 degrees C and aerated with 95% O(2) and 5% CO(2) for the measurement of isometric force. In Ca-free solution with Ethylene glycol-bis (ss-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA) (2 mM) the contractions produced by 5-HT (10(-6) M) and KCl (40 mM) decreased significantly. Afterwards, HUA rings were treated with 5-HT and KCl in repeated manner in Ca-free medium. In contrast to KCl, 5-HT induced contractions reduced in each application, progressively. Levcromakalim (10(-4) M) abolished the contractions elicited by 5-HT. On the other hand, levcromakalim had a little but significant inhibitory effect on KCl induced contraction in Ca-free medium. These results suggest that Ca(2+) is not the only transduction pathway in KCl produced contractions of HUA smooth muscle cells.

Levcromakalim decreases cytoplasmic Ca2+ and vascular tone in basilar artery of SAH model dogs

We investigated the effects of levcromakalim, a K+ channel opener, on [Ca2+]i and the contractile force of basilar arteries obtained from normal dogs and subarachnoid hemorrhage (SAH) dogs. The responsiveness to serotonin was increased more in the SAH group than in the control group. Levcromakalim decreased the resting [Ca2+]i and force more profoundly than did a Ca2+ channel blocker, nicardipine, and these effects were more prominent in the SAH group than in the control group. Levcromakalim diminished the increases in [Ca2+]i and contractile force induced by serotonin more profoundly than nicardipine did, and these effects were equal in both groups. The effects of levcromakalim were not inhibited by iberiotoxin but were antagonized completely by glibenclamide. These results suggest that levcromakalim-induced opening of adenosine triphosphate (ATP)-sensitive K+ (K(ATP)) channels reduces [Ca2+]i more effectively than does nicardipine and that levcromakalim exerts the vasodilator effects under the condition in which large conductance Ca2+-activated K+ (BK) channels are blocked with iberiotoxin. Consequently, K+ channel openers like levcromakalim may be useful drug candidates to treat delayed cerebral vasospasm after SAH.