Cyclic AMP levels were measured in brains of 21 cats after occlusion of a middle cerebral artery by a transorbital approach. Brain samples for determination of cAMP by a protein binding radioassay were obtained from the ischemic and contralateral temporal lobes before sacrifice t, 3, and 24 hours after occlusion of the right middle cerebral artery. At I hour, no difference between the 2 sides was observed; a mean of 17.4 pmoles/mg protein was observed from the side of the occlusion and 18.9 pmoles/mg protein from the contralateral side. At 3 hours, a mean value of 8.9 pmoles/mg protein on the ischemic side and a level of 21.7 pmoles/mg protein on the contralateral side were observed. At 24 hours, the cAMP level on the ischemic side remained below the nonischemic side; the values obtained were 13.7 pmoles/mg protein compared to 27.9 pmoles/mg protein. These changes in cAMP as early as 3 hours after the onset of ischemia, when such a lesion is reversible, may indicate that an initial step in the alteration of cellular metabolism following ischemia is due to membrane perturbation and altered production of this second messenger.
ASJC Scopus subject areas
- Clinical Neurology
- Cardiology and Cardiovascular Medicine
- Advanced and Specialized Nursing