Contractile responses of pial arterioles in gerbils with unilateral carotid ligation.

Studies were made in an effort to detect enhanced vasoconstriction ipsilateral to a ligated common carotid artery. No effect of ligation was found on the response to topically administered serotonin, norepinephrine or prostaglandin F2 alpha, in the gerbil in spite of varying a number of parameters, including anesthesia, percent of inspired oxygen, time elapsed following ligation, or body temperature at time of examination. The response was not influenced by the presence or severity of stroke symptoms. A stronger and less specific constrictor, BaCl2, did elicit a difference between the contractile response of ligated and sham operated gerbils. In 13 of the 18 studies, BaCl2 produced a greater constriction in the ligated gerbils, and in 9 of these studies that difference was statistically significant. In only one study was there a statistically significant contrary result. The enhanced contractile response to BaCl2 could not be related to the presence or severity of symptoms or to any other of the variables mentioned above. This suggests that it was probably related to reduced intraluminal pressure distal to the ligation.