The world's first wiki where authorship really matters (Nature Genetics, 2008). Due credit and reputation for authors. Imagine a global collaborative knowledge base for original thoughts. Search thousands of articles and collaborate with scientists around the globe.

wikigene or wiki gene protein drug chemical gene disease author authorship tracking collaborative publishing evolutionary knowledge reputation system wiki2.0 global collaboration genes proteins drugs chemicals diseases compound
Hoffmann, R. A wiki for the life sciences where authorship matters. Nature Genetics (2008)
 
 
 
 
 

Nature of [Ca2+]i transients during ventricular fibrillation and quinidine treatment in perfused rat hearts.

We studied intracellular Ca2+ concentration ([Ca2+]i) and the electrocardiographic signals during pacing-induced ventricular fibrillation (VF) and quinidine treatment (0.4 mg/min) using surface fluorometry in indo 1-acetoxymethyl ester (AM)-loaded perfused rat hearts. [Ca2+]i was evaluated as the indo 1 fluorescence ratio (F400/F510) and expressed as a percentage of the control amplitude of F400/F510 transients. F400/F510 increased to approximately 250% during 2- (n = 14) or 20-min (n = 9) VF. Quinidine significantly decreased F400/F510 by 60% after 2-min VF; however, this effect was blunted after 20-min VF. After 2-min VF, F400/F510 and left ventricular pressure recovered almost to the control level. However, recovery of F400/F510 and ventricular function was poor after 20-min VF. The relationship between [Ca2+]i and the electrocardiogram (ECG) during VF was evaluated by power spectrum analysis of F400/F510 and ECG signals. During VF (25 +/- 3 Hz) with high irregularity, there were no clear [Ca2+]i transients (n = 110). When the cardiac rhythm (22 +/- 3 Hz) was regular, including ventricular tachycardia, there were recognizable [Ca2+]i signals with dominant frequencies that were the same (n = 2), one-half (n = 12), or one-third (n = 1) of the ECG frequencies. The highest frequency of the [Ca2+]i transients was 19 Hz. During quinidine treatment, the VF rate decreased significantly, and clear [Ca2+]i transients were noted in all records responding to every one or two ECG signals. The conclusions were the following: 1) [Ca2+]i responds to electrical signals rapidly (up to 19 Hz) during VF. This fast [Ca2+]i response is a probable cause of high [Ca2+]i during VF. 2) Quinidine decreased [Ca2+]i after 2-min VF possibly in part by slowing the VF and [Ca2+]i transients rates. 3) 20-min VF caused [Ca2+]i overload and poor functional recovery after defibrillation.[1]

References

  1. Nature of [Ca2+]i transients during ventricular fibrillation and quinidine treatment in perfused rat hearts. Kojima, S., Wikman-Coffelt, J., Wu, S.T., Parmley, W.W. Am. J. Physiol. (1994) [Pubmed]
 
WikiGenes - Universities