LONG-TERM PERFUSION OF THE CEREBROVENTRICULAR SYSTEM OF DOGS WITHOUT LEAKAGE TO THE PERIPHERAL-CIRCULATION

Methods developed previously for studying the effect of cerebroventric ular injection or ventriculocisternal perfusion of test substances are unsatisfactory because the test substance is not confined to the cent ral compartment. Most likely the test substance enters the peripheral circulation via the arachnoid villi. The purpose of this paper is to d escribe a method for perfusing the cerebroventricular system of consci ous dogs without passage of test substances to the peripheral circulat ion. With the method described, the mean (+/-SE) cerebroventricular pr essure in conscious dogs was 7.4 +/- 0.8 cmH(2)O (n = 16), and the mea n (+/-SE) production of cerebrospinal fluid (CSF) was 25 +/- 0.3 mu l/ min (n = 16). Endogenously occurring migrating myoelectric complexes ( MMCs) of the small intestine were recorded in dogs before catheters we re implanted in the left and right lateral ventricles and the fourth v entricle and after catheter implantation during cerebroventricular per fusion with artificial CSF alone or with CSF containing sulfated (S-CC K-OP) or nonsulfated cholecystokinin octapeptide (NS-CCK-OP). Only cer ebroventricular perfusion with S-CCK-OP (1.2 pmol.kg(-1).min(-1); n = 20) replaced spontaneously occurring MMCs with a fed-like pattern of m yoelectric activity. The results suggest that replacement of the fasti ng pattern of myoelectric activity with a fed-like pattern in the fast ed dog was mediated by CCK-A receptors located in one or more brain nu clei surrounding the third ventricle.