Summary1. The anaesthetic, cardiovascular, respiratory and adverse effects produced by the intravenous injection of CT 1341, thiopentone, methohexitone, pentobarbitone, propanidid and ketamine have been compared in unrestrained cats prepared with chronically implanted venous and arterial cannulae. Aortic blood pressure and heart rates were monitored before, during and after loss of consciousness. 2. CT 1341 produced rapid induction of anaesthesia followed by moderately rapid recovery, was active over a wide range of doses and caused minimal respiratory depression and few adverse effects. It caused an initial shortlasting tachycardia and fall in aortic blood pressure succeeded by a secondary depressor response. 3. The safety margin was narrower with the barbiturate drugs than with CT 1341, and large doses induced apnoea and respiratory depression. Small doses of methohexitone elicited excitatory effects and large doses caused severe respiratory and circulatory depression, and recovery from anaesthesia was protracted. 4. Propanidid induced short-lasting light anaesthesia. The safety margin was narrowest with this drug and induction was associated with adverse circulatory, respiratory and other effects. 5. Ketamine was active over a wide range of doses but exhibited qualitatively different properties from the other anaesthetics. Induction was slower after small doses and these produced circulatory stimulation, catatonia and bizarre behavioural effects. Large doses caused respiratory and circulatory depression and recovery was protracted. 6. It is concluded that CT 1341 has a wider therapeutic latitude, produces less respiratory depression and has other advantages over the currently used intravenous anaesthetics.
A new semi-synthetic antibiotic, 7-[(2-thienyl)acetamido]-3-(1-pyridylmethyl)-3-cephem-4-carboxylic acid betaine (cephaloridine; Ceporin, Glaxo), has recently been prepared from cephalosporin C.[7IC2CONHI!-S Cephaloridine possesses low toxicity for most species of laboratory animals, but in some of them administration of the antibiotic results in the development of a characteristic proximal renal tubular necrosis (Atkinson et al., 1966b). The study recorded here was designed to investigate the mechanism of urinary excretion of cephaloridine and to determine its effects on renal function in anaesthetized animals.
METHODSEffects ofcephaloridine on renalfunction in anaesthetized cats and dogs Cats. Cats of each sex and weighing between 1.9 and 4.1 kg were anaesthetized by intraperitoneal injection of chloralose (80 mg/kg) and pentobarbitone sodium (10 mg/kg). A cannula was inserted in the trachea, and the left external jugular vein and right femoral artery were prepared for cannulation. A short midline incision was made in the lower abdomen and a urethral catheter was inserted for urine collection. After securing the cannula by ligatures, the abdomen was closed. The blood vessels were cannulated, and heparin (1,000 units/kg) was injected intravenously. Blood pressure was recorded from the carotid artery by a mercury manometer. Mannitol (300 mg/kg) was given intravenously, and 5% mannitol in 0.9% saline was infused intravenously at 0.75 ml./min throughout the experiment to ensure moderate diuresis. Control blood (from femoral artery) and urine samples were collected during the subsequent stabilization period of approximately 1 hr.
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