title: Experimental hypothyroidism increases plasminogen activator inhibitor activity in rat plasma.
abstract: The aim of the present study was to investigate whether hypothyroidism would affect the components of the rat plasma fibrinolytic system. Hypothyroidism was induced by feeding rats a thiouracil-containing diet for 2 weeks. During this period, half of the animals received subcutaneous injections of L-thyroxine (20 micrograms/kg daily) to restore thyroid hormone levels. Groups of euthyroid rats were similarly treated with L-thyroxine. Plasma tissue-type PA (t-PA) activity was not affected by thyroid status. Plasma urokinase-type PA (u-PA) activity was significantly decreased by the thiouracil-containing diet; however, this effect was not abolished by L-thyroxine. Plasminogen, alpha 2-antiplasmin and fibrinogen were not affected by hypothyroidism. In the hypothyroid group, plasma PAI activity was significantly increased; no such increase was found in animals simultaneously receiving L-thyroxine. Plasma PAI activity correlated with T3 (r = -0.586; P < 0.005) and cholesterol (r = +0.737; P < 0.001); in multiple regression analysis, however, the correlation between PAI activity and T3 was not significant. The increase in plasma PAI activity during hypothyroidism may thus not be a direct effect of the thyroid hormone, but an indirect one through some other, possibly cholesterol related, component.
authors.affiliation: Gaubius Laboratory IVVO-TNO, Leiden, The Netherlands.
authors.forename: T
authors.initials: T
authors.lastname: Padró
authors.forename: C M
authors.initials: CM
authors.lastname: van den Hoogen
authors.forename: J J
authors.initials: JJ
authors.lastname: Emeis
mesh_terms: D000818:Animals; D002784:Cholesterol / Q000097:blood; D007037:Hypothyroidism / Q000097:blood* / Q000139:chemically induced; D008297:Male; D015849:Plasminogen Inactivators / Q000097:blood*; D051381:Rats; D017208:Rats, Wistar; D013889:Thiouracil; D013974:Thyroxine / Q000097:blood / Q000494:pharmacology; D010959:Tissue Plasminogen Activator / Q000378:metabolism; D014284:Triiodothyronine / Q000097:blood; D014568:Urokinase-Type Plasminogen Activator / Q000097:blood
chemical_list: D015849:Plasminogen Inactivators; D014284:Triiodothyronine; D013889:Thiouracil; D002784:Cholesterol; D010959:Tissue Plasminogen Activator; D014568:Urokinase-Type Plasminogen Activator; D013974:Thyroxine