Cadmium injected to mice provokes an acute disaggregation of hepatic polyribosomes. The effect appears within 15 min, it is maximal after 1 h and then gradually disappears. The reaggregation of polyribosomes takes place 6–12 h after injection. The disaggregation of polyribosomes is linear with log doses in a range of 7.25–20 µmol/kg CdCl₂. Cycloheximide pretreatment prevents the disaggregation of polyribosomes in the livers of cadmium-treated mice.

H i s t o c h e m i c a l Detection of the Position of MetalT h e d e t e c t i o n of t h e precise position of t h e microelectrode in t h e tissue which is being e x a m i n e d is of v i t a l i m p o r t a n c e in t h e analysis of electrophysiological processes on t h e spot e x a m i n e d , as well as in electrical stimul a t i o n of t h e d e t e r m i n e d biological structure, i.e. in working w i t h b o t h d e r i v a t i n g a n d s t i m u l a t i n g electrodes.O u r work covering t h e e l e c t r o l y m p h o c a r d i o g r a m(ELCG) of t h e sacral l y m p h frog's h e a r t s (Rana esculenta)b y m e a n s of t h e m e t a l microelectrode h a s c o n f i r m e d this, a n d it p r o m p t e d us in t h e first place to d e t e r m i n e precisely t h e position of t h e electrodes. I n order to accomplish this, we i n t r o d u c e d iron from t h e microelectrode into t h e tissue b y electrolysis, a n d s u b s e q u e n t l y d e t e r m i n e d t h e presence of iron in t h e tissue b y histochemical m e t h o d s in serial sections of t h e tissue. Metal microelectrodes (diameter a b o u t 5 it) were m a d e of stainless steel wire (36 S W G Allen a n d H a n b u r y s Ltd.) d i a m e t e r 0.3 ram, according to B U R E~ et a l ) .T h e frog was a n a e s t h e t i z e d w i t h u r e t h a n e a n d t h e skin from t h e sacral l y m p h h e a r t s removed. Using t h e stereomicroscope, t h e microelectrode was inserted a t t h e spot w h i c h showed t h e m o s t i n t e n s i v e pulsations.After registering E L C G t h e electrolysis was carried o u t b y D.C. of 0.5 V i n t e n s i t y d u r i n g 15 sec. T h e positive pole was c o n n e c t e d w i t h microelectrode a n d t h e n e g a t i v e pole w i t h indifferent electrode inserted in t h e lower l i m b on t h e opposite side. T h e l y m p h h e a r t was excised a n d n a t i v e frozen sections were m a d e a n d t h e histochemical reaction o n iron (Fe II) p e r f o r m e d ~. MicroelectrodeThis m e t h o d gave t h e positive r e a c t i o n to iron (dark blue colour) in t h e e x a m i n e d tissue w i t h i n a radius of 90/~ from where t h e microelectrode h a d b e e n situated. F u r t h e r work is in progress. Zusammen/assung.Die M e t h o d e der h i s t o c h e m i s c h e n D e t e k t i o n d e r Lage d e r M e t a l l m i k r o e l e k t r o d e wird beschrieben. N a c h d e m die A k t i o n p o t e n t i a l e registriert word e n sind, wird das Eisen aus d e r Mikroelektrode d u r c h E l e k t r o l y s e ins Gewebe eingefiihrt, u n d anschliessend in S e r i e n s c h n i t t e n m i t h i s t o c h e m i s c h e n M e t h o d e n nachgewiesen.S. GAMULIN, LJ. GuRovld a n d P. M e s u r e s en continu et in situ des pH art@riel et v e i n e u x profonds chez le M a m m i f~r eL a d 6 t e r m i n a t i o n du p H s a n g u i n doit de t o u t e n@cessit6 ~tre faite sans pr61~vement de sang, de fa~on non-diff6r6e, au lieu m 6 m e off Yon d@sire c o n n a i t r e Ia v a l e u r du p a r am&tre p h...