REDUCED EXPRESSION OF CALPONIN IN CANINE BASILAR ARTERY AFTER SUBARACHNOID HEMORRHAGE

Calponin, an actin- and tropomyosin-binding protein, has been characte rized as an inhibitory factor in the smooth-muscle actomyosin activity . The level of calponin was determined in canine basilar arteries in a double-haemorrhage model. Thirty dogs were assigned to three groups: day 0 group, control; day 2 group, dogs sacrificed 2 days after cister nal injection of blood; and day 7 group, does given double cisternal i njections of blood and sacrificed 7 days after the first injection. Co nstriction of the basilar artery was confirmed by arterial angiography . Portions of the affected arteries or the corresponding region in con trol animals were solubilized for sodium dodecylsulphate-polyacrylamid e gel electrophoresis and Western blotting. A major band corresponding to calponin was seen at 34 kD in the basilar artery extracts using ch icken gizzard polyclonal antibodies. The densitometer values of the ba nd on Coomassie blue-stained gels were expressed as percentages of day 0 control values. The signals of day 2 and day 7 samples were 47%+/-2 0% and 23%+/-12%, respectively (mean+/-standard deviation). The propor tions of calponin to actin/tropomyosin in the day 0, day 2, and day 7 groups were 13%+/-6, 6%+/-2%, and 4%+/-2%, respectively. The reduced e xpression of calponin may be related to sustained contraction during c erebral vasospasm.