PubMed Health⌕ Search

Biomedical subjects

C Achenbach

Publications and source records attributed to C Achenbach.

22 records · Page 2Linked to original sources
PubMed1980

Effects of cryptand 2.2.1Py on the fast sodium current in cardiac Purkinje fibers.

For study of dose-dependent influence on sodium current, sheep heart Purkinje fibers were perfused with a cryptand (2.2.1Py) and measured for resting potential, overshoot, amplitude and duration of action potential, refractory period, and rate of rise. Concomitant investigation was made by voltage clamp. The cryptand was found to depress maximal rate rise with increase of concentration and induce shift toward negative potential with increase of dose. Also, effect on sodium current kinetics was observed but not on resting potential. The findings indicate that 2.2.1Py action probably is not primarily ionophores, negating the idea that cryptands promote transmembrane ion exchange.

Action Potentials↗
PubMedDate not supplied

A voltage clamp study of the effects of AR-L 115 BS on the pacemaker current of cardiac Purkinje fibres.

The new cardiotonic agent AR-L 115 BS was investigated by means of the double-micro-electrode voltage clamp technique on sheep cardiac Purkinje fibres. Clinical and pharmacological studies show that AR-L 115 BS increases heart rate as a side effect at medium to high therapeutic doses. The classical analysis of the pacemaker current was therefore performed to study the possible mechanism of this effect at a cellular level. The kinetic parameter s infinity and the reversal potential of the pacemaker current were shifted in the depolarizing direction after exposure to AR-L 115 BS. Peak values of the fully activated pacemaker current were either increased or diminished, while potassium leakage was slightly increased. These results are not related to the action of AR-L 115 BS on beta-adrenergic receptors but possibly due to enhanced intracellular calcium (see third paper in this series). Despite its tendency to increase heart rate, high concentrations of AR-L 115 BS should not be expected to promote arrhythmias in the Purkinje system since the electrophysiological effects tend to counteract each other.

Animals↗
PubMedDate not supplied

Quantitative investigations on the diaplacental transfer of thallium by field desorption mass spectrometry.

The placental transfer of thallium cations in pregnant mice was investigated by determining the thallium concentrations in fetal and maternal tissue 0.5 to 24 h after application of thallium. The maternal dose of thallium was 8 mg/kg body weight throughout. Uterus and fetus were found not to differ from other organs like heart and liver in time course and magnitude of thallium uptake with an initial surge during the first few hours of exposure to thallium and a rapid decrease to steady 12 and 24 h values somewhat lower than those found in the kidney. Diaplacental transfer is therefore assumed comparatively rapid and a specific placental barrier for thallium does not seem to exist. For the determination of thallium concentrations Field Desorption Mass Spectrometry was utilized as a reliable, fast and sensitive method for the analysis of metal cations in biological material. This method does not require extensive pretreatment of the tissue and total sample amounts in the range of milligrams and less are sufficient for quantitative analysis.

Animals↗