Phalloidinwirkung an der erythrocytenfrei perfundierten Rattenleber

Summary

1.The first symptom of phalloidin poisoning in the isolated rat liver is an increase in the light scattering of the liver tissue, which begins 2–3 min after exposing the tissue to the toxin. Simultanously the oxygen consumption increases, reaching a new plateau 15±11% above the starting level after 10 min. 2.In a low-Ca medium (2·10⁻⁴M Ca⁺⁺) phalloidin produces a Ca⁺⁺ release of 0,22 ± 0,08 ΜM Ca/g liver which starts after 2–4 min and finishes after 15 to 20 min. In the presence of 1.4·10⁻³M Ca⁺⁺ there is a transient Ca⁺⁺ release of about 0.1 ΜM Ca/g liver (only detectable by indirect methods) followed probably by a slow Ca⁺⁺ uptake. 3.At 27‡ C a potassium efflux starts 11.5 ± 3.5 min after phalloidin, preceeded by an increase in the weight of the liver starting after 6 ± 1,5 min. 4.EDTA (10⁻³ M, in a medium containing 2·10⁻⁴M Ca⁺⁺ and 5·10⁻⁴ M Mg⁺⁺) produces a swelling of the liver, a Ca⁺⁺ release (0.3 ΜM/g liver after 30 min) and a limited K⁺ release (11±4 ΜM/g liver after 30 min).

Phalloidin has no further effect on the Ca or K content of the liver. The only effect of phalloidin in the presence of EDTA is a small increase of the light scattering of the liver tissue. 5.Addition of EDTA (0.4–1.4 mM free EDTA) to a phalloidin poisoned liver which has lost most of its potassium, leads to a re-uptake of the released K⁺ of up to 75% in 120 min. The K⁺ uptake is not correlated with a decrease in liver weight. 6.A decrease of temperature from 27‡ to 19‡ C diminishes the rate of K⁺⁺ release caused by phalloidin to 33±15% of the rate at 27‡. The analogous changes of the rate of the K⁺ re-uptake are in the same range.