Disclosed are compounds of the formula: or the pharmaceutically acceptable non-toxic salts thereof wherein: A, B, C and D are N or CH; X is a bond or (un)substituted CH2; R1 is lower alkenyl or (un)substituted lower alkyl; R3 is lower alkyl; and R2, R4, R5, and R6 are variables defined herein; which compounds are useful in the diagnosis and treatment of renal diseases, heart failure, hypertension, Meniere's disease, vaginal inflammation and pain, peripheral circulatory disorders, climacteric disturbance, retinochoroidal circulatroy disorders, myocardial ischemia, myocardial infarction, postmyocardial infarction syndrome, angina pectoris, restenosis after percutaneous transluminal coronary angioplasty, hepatitis, liver cirrhosis, pancreatitis, ileus, diabetes, diabetic complications, male infertility or glaucoma, or for the increase of permeability of blood-brain barrier, pain, asthma, and rhinitis.