The influence of age on the lipolytic effect of glucagon and epinephrine, and on the antilipolytic effect of prostaglandin El will be studied in vitro using adipose tissue slices from geese of different age. Lipolytic activity will be determined by measuring both free fatty acids and glycerol production. Adipose cell size will be measured in order to determine whether the age-related changes in lipolytic response can be explained by changes in cell size. The effect of changing cell size on the lipolytic response will also be studied by comparing tissues of normally fed and of starved animals. The influence of age on the potentiation by theophylline of glucagon- and epinephrine-induced lipolysis and on the lipolytic effects of CAMP and DBCAMP will be studied. Experiments will be performed in order to determine whether age influences the rate of removal of plasma free fatty acids in vivo.