This study was conducted to determine the effects of clofilium phosphate and bretylium tosylate on ventricular defibrillation threshold. Dogs were anesthetized with pentobarbital and subjected to repeated fibrillation-defibrillation episodes. Defibrillation thresholds were determined at 15-min intervals using underdamped 5-6 msec sinusoidal current shocks, from 30 min before drug injection to 120 min after injection. Eight dogs were given clofilium phosphate (0.34 mg/kg, iv). Another 10 dogs were given bretylium tosylate (10.0 mg/kg, iv). Both drugs lowered defibrillation threshold from 15-90 min after injection. The maximum clofilium effect was a 31% decrease in threshold current and a 54% decrease in threshold energy. The greatest decrease in defibrillation threshold produced by bretylium was 16% for current and 31% for energy. These drug induced changes in defibrillation threshold are of potential clinical benefit, if they occur in human subjects at doses that are effective for control of ventricular arrhythmias.

No abstract

Effects due to maternal environment, sex of materDal environment was significant (P < lamb and litter size on the growth of lambs 0.05) at birth. Howevet, after 90 days the were studied in lambs produCed by reciprocal difference was small and nonsignilgant ^Llt!9I crossbreeding of Linioln and -Southdown size had a highly significant effect (P <0.001)sheep. At bi-rth, maternal environment (Lin-on body weight, cannon bone length and coln vs. Southdown) had a highly sigfficant cannon bone width at birth and postnatally. (P < 0.001) effect on the fetal weight. The Birth differences due to sex of lamb were difference at birth increased slightli at 40 rather small in all three traits, but increased days (weaning) but at 150 and 190 days the as the lambs grew older. The effects of breed difference wai small and nonsignificant-. The of sire on body weight and cannon bone effect of maternal environmenl on cannon length were relatively small at birth but inbone length, although small compared with creased with age. Breed of sire, however,_ had body weight, had a significant efiect (P ( no effect on cannon bone width at birth or 0.05) extending to at least 150 days of age. postnatally but interacted significantly,with The difference in cannon bone width due to breed of dam on birth and weaning weight.

The concentration of blood plasma urea nirrogen (BUN) femoleq_respegtiye-ly. The average rates of g"i" fof these jro"ps-*"i"-O.ll, 0.28,0.26 and 020 kg per dav. resp-ectivelv. Iianneered from"thes'e snrdies thei !"s pci day, '"-'p%.tiuiiy.-T;pp;;d i;6-1-n*! 't'aies that at any given weight, the more marure animals at that weieht tended to have higher B(rN concenrrations and a higher rate of increase of-BUN with weight.