A novel nitrogenous fused bicyclic compound represented by the following
general formula [1] or a pharmacologically acceptable salt of the
compound. They have excellent SK channel blocking activity and are useful
as a medicine. [I] (In the formula, R.sup.0 represents hydrogen,
halogeno, etc.; R.sup.1 represents a group represented by the formula (a)
or (b); A represents a group represented by the formula (X) or (Y);
D.sup.1, D.sup.2 and D.sup.3 each represents N or CH; R.sup.2 represents
halogeno or optionally halogenated lower alkyl, etc.; R.sup.3 represents
hydrogen or lower alkyl; and Q represents lower alkylene.)