Vasomotor responses recorded using the in situ perfusion of a portion of the rat cerebral circulation

A simple method whereby an area of the rat cerebral circulation can be perfused in situ in the dead animal has been developed. A modified Krebs/Henseleit perfusate was passed at a constant flow rate through one internal carotid artery and recovered from the transverse sinus following ligature of the arterial system of the opposite side and all venous returns to the heart. Rubber latex injections indicated that the main perfusion pathway was unilateral via the middle, anterior, and posterior cerebral arteries. The basilar and cerebellar arteries were not involved. Vasoconstrictor substances, such as 5-hydroxytryptamine (5HT), noradrenaline, and related catecholamines, gave reproducible, dose-related responses, when tested over experimental periods of 4-5 hrs. Although the preparation had no intrinsic vascular tone, vasodilator substances, such as acetylcholine, isoprenaline, histamine, or the purines, adenosine, ATP, ADP, and AMP, could be tested against various levels of tone induced by the addition of 5HT to the perfusate. On the basis of these preliminary results, the preparation appears suitable for qualitative and quantitative investigations of the responses of the rat cerebral circulation to a wide range of vasoactive substances.