Procainamide in the dog: antiarrhythmic plasma concentrations after intravenous administration

Procainamide hydrochloride was administered to ouabain-intoxicated dogs to determine an antiarrhythmic plasma concentration of procainamide. Ventricular arrhythmias were produced in dogs following intravenous injections of ouabain. After a sustained ventricular tachycardia was achieved, procainamide was administered and plasma samples collected for assay. Plasma procainamide was assayed by fluorescence polarization immunoassay. Procainamide was administered at increasingly higher constant rate infusions in order to achieve intermittent, steady-state plasma concentrations. Infusion rates were calculated on the basis of previous pharmacokinetic information. All six dogs that received procainamide converted to a normal sinus cardiac rhythm after attaining a mean plasma concentration of 33.8 micrograms/ml with a range of 48.5 micrograms/ml-25.0 micrograms/ml. It was observed that the computer-generated prediction of plasma concentrations based upon previous pharmacokinetic data produced an underestimate of the actual plasma concentrations. These data may suggest that plasma concentrations of procainamide for controlling some cardiac arrhythmias in dogs may be higher than plasma concentrations cited for human patients.     

Effect of fasting on capillary blood flow in sheep

Capillary blood flow rate was measured in 29 tissues in two hourly fed and 26 hour fasted Blackface and Clun lambs using the radiolabelled microsphere technique. Blood flow declined with fasting in alimentary tract, skin of the ear and some of the larger skeletal muscles. It was concluded that capillary perfusion in nerve tissue was not affected by fasting whereas tissues principally responsible for energy absorption, expenditure and retention can experience a fall in capillary blood flow during fasting.     

A COMPARISON OF MANUAL AND AUTOMATIC ULTRASOUND-GUIDED BIOPSY TECHNIQUES

A manual, ultrasound-guided biopsy technique was compared to a new automatic method using a new biopsy device. The liver and the left kidney of 10 dogs were biopsied using the two methods. The specimens from the biopsies were compared for size and quality. Results demonstrate that larger and higher quality samples were obtained with the new automatic method.     

Morphologic studies of uveoscleral outflow in normotensive and glaucomatous beagles with fluorescein-labeled dextran

Aqueous humor leaves the anterior chamber through 2 pathways: the trabecular meshwork of the iridocorneal angle and the unconventional uveoscleral route. In the latter route, aqueous humor leaves the anterior chamber, passes caudally through the trabecular meshwork and sclerociliary cleft to enter the supraciliary and suprachoroidal spaces. The fluid is absorbed by the choroidal and scleral circulation. Fluorescein-labeled dextran was slowly infused into the posterior chamber of healthy and glaucomatous Beagles for 30 minutes. The eyes were fixed in a mixture of 70% alcohol and formalin, placed in epoxy resin for histologic evaluation, and examined by fluorescent microscopy. Fluorescence was detected in the healthy dogs throughout the uveoscleral pathway. In the glaucomatous dogs, the uveoscleral outflow was decreased or completely absent.     

Dysentery caused by Escherichia coli (S102-9) in calves: natural and experimental disease

A dysentery syndrome was recognized among the Institute's calves at 18 to 21 days of age. It was reproduced experimentally in gnotobiotic calves with an atypical Escherichia coli (S102-9) isolated from the affected calves. In both natural and experimental disease the calves passed copious bright red blood in the feces and developed diarrhea. Walls of the colon and rectum were thickened, and the mucosa was reddened and covered by an exudate that contained mucus and blood clots. Bacteria were seen closely adherent to the luminal surfaces of enterocytes, often in cup-shaped depressions or on cytoplasmic pedestals. Microvilli were distorted, disorientated or absent. There was exfoliation of infected enterocytes and a mild acute inflammation of the underlying lamina. In two of five calves with natural disease, the adherent bacteria did not stain by the immunoperoxidase method with antisera raised against E. coli (S102-9). This indicated that there was possibly more than one bacterial cause of the syndrome. Lesions in experimentally infected calves were indistinguishable from those produced by some E. coli which are enteropathogenic for man, rabbits, and pigs.