Passage of Intravenously Infused Atropine Into Perfused Cerebral Ventricles and Subarachnoid Space

Abstract

Stern & Gautier (1921) detected atropine in the cerebrospinal fluid of the dog and of the rabbit, after its intravenous or intracarotid injection. The present experiments were undertaken to see if in the cat also atropine passes from the blood stream into the cerebrospinal fluid, and if so, to determine the rate of its output in the effluents obtained on perfusion of various parts of the cerebral ventricles and subarachnoid space.Our experiments with cats show that atropine, during its intravenous infusion, appears in the cerebrospinal fluid, and further it was found in the effluents from both the perfused cerebral ventricles and the perfused subarachnoid space. There was no significant difference between the output from the cerebral ventricles and that from the subarachnoid space. METHODSCats weighing 1.5 to 4 kg were anaesthetized with chloralose, 70 mg/kg, injected intravenously under ethyl chloride and-ether anaesthesia. The trachea was cannulated. For the atropine infusion a cannula was inserted in the right femoral vein. The atropine sulphate in 0.9% saline was infused at 0.2 ml./min with a continuous slow injector at rates of 1, 10 or 25 pLg/kg/min. Blood samples were obtained from the left femoral artery, which was dissected free and clamped; an opening was made in the artery for the insertion at intervals of 1 hr of a polythene tube, through which the samples were collected into tubes containing heparin, and then immediately centrifuged and the plasma separated. The plasma was kept at room temperature (25 to 300 C) if assayed on the same day, or in the refrigerator (at 4' C) for assay on the next day.Collection of cerebrospinal fluid. A cisternal cannula similar to one described by Bhawe (1958) was inserted into the cisterna magna. The cannula consisted of a 20 S.W.G. hypodermic needle with the butt removed and a small length of polythene tube attached. The free end of the polythene tube was closed with a small glass stillete. Cerebrospinal fluid samples were collected every hr by removing the glass stillete and allowing 0.5 to I ml. of cerebrospinal fluid to flow into a test tube. The stillete was then replaced.

Passage of intravenously administered tubocurarine into the liquor space in man and dog

“…The methods were the same as those described for cats -by Bhattacharya & Feldberg (1958a) for perfusion from the lateral ventricle and by Haranath, Premalatha & Sunanda-bai (1966) for perfusion from the spinal subarachnoid space. The Collison cannula used was that originally described by Feldberg & Sherwood (1953) as modified by McCarthy & Borison (1966).…”

Intracarotid Injections and Infusions of Cholinomimetic Drugs and Their Antagonists in Conscious Dogs

“…The drugs may reach the brain substance from the blood stream either by crossing the blood-brain barrier or by first entering the cerebrospinal fluid, and later penetrating the brain. In cats atropine was shown to reach the cerebrospinal fluid from the blood stream by Haranath, Premalatha & Sunanda-Bai (1966). The passage of d-tubocurarine into the cerebrospinal fluid in man after its systemic administration was described by Mahfouz (1949), but was doubted by Cohen (1963).…”