pituitrin and bretylium

Shock-resistant ventricular fibrillation is defined as ventricular fibrillation persisting after three defibrillation attempts. In approximately 10 to 25% of all cardiac arrests, shock-resistant ventricular fibrillation develops, and 87 to 98% of these patients die.. In the treatment of shock-resistant ventricular fibrillation, defibrillation using biphasic waveforms is considered as an intervention of choice. Intravenous amiodarone is also acceptable, safe, and useful, based on evidence from two randomized clinical trials. Intravenous vasopressin is acceptable and probably safe and useful, but the evidence supporting this recommendation is coming from a small, randomized clinical trial. Procainamide is acceptable but not recommended. In the presence of acute myocardial infarction and recurrent ventricular fibrillation, if all other therapies fail, beta-blockers can be considered. Magnesium, lidocaine, and bretylium are not recommended in the treatment of shock-resistant ventricular fibrillation.. Biphasic defibrillation and intravenous amiodarone are useful in shock-resistant ventricular fibrillation.

Topics: Adrenergic beta-Antagonists; Amiodarone; Anti-Arrhythmia Agents; Bretylium Compounds; Cardiopulmonary Resuscitation; Electric Countershock; Heart Arrest; Hemodynamics; Humans; Lidocaine; Magnesium; Procainamide; Vasoconstrictor Agents; Vasopressins; Ventricular Fibrillation

The patch-clamp technique for the recording of single-channel currents was used to investigate the activity of ion channels in the intact epithelium of the toad urinary bladder. High resistance seals were obtained from the apical membrane of tightly stretched tissue. Single-channel recordings revealed the activity of a variety of ion channels that could be classified in 4 groups according to their mean ion conductances, ranging from 5 to 59 pS. In particular, we observed highly selective, amiloride-sensitive Na channels with a mean conductance of 4.8 pS, channels with a similar conductance that were not Na-selective and channels with mean conductance values of 17-58 pS that were mostly seen after stimulation of the tissue with vasopressin or cAMP. When inside-out patches from the apical membrane were exposed to 110 mM fluoride, large conductances (86-490 pS) appeared.

Topics: Amiloride; Animals; Bretylium Compounds; Bufo marinus; Cyclic AMP; Electric Conductivity; Electronic Data Processing; Epithelium; Female; Fluorides; In Vitro Techniques; Ion Channels; Membranes; Methods; Models, Biological; Protein Kinases; Sodium Channels; Urinary Bladder; Vasopressins