THE EFFECT OF FASTING AND OR BODY-WEIGHT REDUCTION ON TISSUE-TYPE PLASMINOGEN-ACTIVATOR (T-PA) AND PLASMINOGEN-ACTIVATOR INHIBITOR (PAI-1)/

Ten healthy, physically fit, non-smoking volunteers (9 women, 1 man, a ged 22-55, mean 33 years) with normal body weight and blood lipids wer e included in the study. During a fasting period of 8-21 (mean 16) day s they took only drinks and lost 5-12 (mean 7) kg of body weight. Rest ing and post-20 min upper arm venous occlusion blood samples were obta ined 1-2 days before and on the last day of the fast. Fasting did not significantly affect blood lipids. After fasting an increase in testin g euglobulin activity (7.4 vs 3.6 mid(-1), p < 0.01), and in tissue-ty pe plasminogen activator (t-PA) activity (215 vs 42 mIU/ml, p < 0.01) was found. A decrease in plasminogen activator inhibitor (PAT) activit y (5.5 vs 7.1 IU/ml, p < 0.07) was indicated, while changes in t-PA an d PAI-1 antigens were not significant. After the fast fibrinolytic res ponse to venous occlusion was enhanced as observed by greater increase in euglobulin activity (40.4 vs 11.6 min(-1), p < 0.02), t-PA activit y (30754 vs 1593 mIU/ml p < 0.01), t-PA antigen (25.9 vs 11.6 ng/ml, p < 0.02), and greater decrease in PAT activity (3.5 vs 0.0 IU/ml, p < 0.01). In ten non-fasting subjects on normal diet, repeated measuremen ts in a period of 13-23 (mean 17) days revealed no significant changes either before or after venous occlusion, It was concluded that in phy sically fit, non-obese subjects fasting and/or body weight reduction h as enhancing effect on resting and post-venous occlusion fibrinolytic activity without significant changes in blood lipids.