Introduction of the closed cranial window technique in gerbils and verification by observation of the effects of specific drugs

The exact mechanisms of cerebral arterial hypoxia are not perfectly defined . Our purpose is to adapt and validate, with drugs well known in rats and r abbits, a closed cranial window technique in gerbils. The method was used w ith seventeen gerbils to measure diameter changes of the pial arterioles un der normoxia (after the topical application of agonists and antagonists of ATP-sensitive and Ca2+-dependent potassium channels), as well as under hypo xia. In normoxia, aprikalim (10(-6) M), a direct activator of ATP-sensitive potassium channels, increases the diameter of pial arterioles by 10+/-2% ( N=17). This effect is inhibited by glibenclamide (10-6 M), but not affected by iberiotoxin (10-6 M), a specific inhibitor of Ca2+-dependent potassium channels. The adenosine-induced dilation by 19+/-5% (N=17) is reduced by 59 +/-16% with iberiotoxin, by 33+/-23% with glibenclamide and inhibited by th eophylline (10(-5) M). In hypoxia (15% O-2), pial arteriole diameters are i ncreased by 24+/-5% (N=17) and partially decreased by the application of gl ibenclamide and iberiotoxin to 59+/-11% and 54+/-5%, respectively. These da ta are similar to those obtained in other species and validate the closed c ranial window technique on gerbils. They indicate that, as for rats and rab bits, both ATP-sensitive and Ca2+-dependent potassium channels are present in gerbil pial vessels and play a role in hypoxia.