Effects of thallium sulfate on cardiovascular and respiratory systems of various animals

Thallium sulfate po or iv de-pressed cardiovascular and respiratory sys-tems of dogs, cats, rats, rabbits, kids and pigeons. These effects were partially di-rect and partially, due to a participation of higher vasomotor and respiratory cen-ters, indirect. but mostly dependent on a decrease of the vasomotor reactivity eva-luated by stimulation of nervous pathways and baroreceptor areas. Experiments in vitro also documented a depression of spontaneous tonic and phasic activity as wellas a depression of the contrac'tion by various mediators (ACh, histamine, 5-HT, norepinephrine, bradykinin, PGF 2a). Thallium is an extremely toxic ion capable to accumulate in the organism. Its toxic effects have heen noted since its dis-covery in 1861. Now thallium salts (es-pecially sulfate) are used as rodenticides and insecticides. Thallium poisonings are associated with cardiovascular changes (hypo-hypertension arrhythmias) which are, particularly in chronic intoxications, due to deterioration of autonomic nervous system(l-3). The mechanism has not yet adequately been defined. The presentstudy was conducted in vivo and in vitro using thallium sulfate. METHODS Adult, or old, 8 and ~ (but not preg-riant) NOS white rats ( 210+13 g), cats (3.2 +0.6 kg), dogs (8.2+0.2 kg), rabbits (2.7+0.4kg), kids (6.5+0.4 kg),'guinea pigs (460+21 g), pigeons (395+18 g) and frogs (26+2g) were fasted (with free access to water) 12 h before experiment. Rhallium sulfate (Merck), l-norepine-phrine bitartrate and d/-isoprenaline sul-fate (C H-Boehringer Ingelheim), acetyl-choline-CI and histamine-CI (Hoffmann-La Roche), nicotine bitartrate (Simes), 5-hydroxytryptaniine creatinin e-sulfate (Sigma), synthetic bradykinin (Sandoz), and PGFZa trometamine (Upjohn). In vivo research: Rats, cats and rab-bits were anesthetized with im ethyl-ure-thane l g/kg while dogs, kids and pigeons with iv pentobarbital-Na 25-30 mg/kg/uterus of virgin.