Detection, Properties, and Frequency of Local Calcium Release from the Sarcoplasmic Reticulum in Teleost Cardiomyocytes

Calcium release from the sarcoplasmic reticulum (SR) plays a central role in the regulation of cardiac contraction and rhythm in mammals and humans but its role is controversial in teleosts. Since the zebrafish is an emerging model for studies of cardiovascular function and regeneration we here sought to determine if basic features of SR calcium release are phylogenetically conserved. Confocal calcium imaging was used to detect spontaneous calcium release (calcium sparks and waves) from the SR. Calcium sparks were detected in 16 of 38 trout atrial myocytes and 6 of 15 ventricular cells. The spark amplitude was 1.45±0.03 times the baseline fluorescence and the time to half maximal decay of sparks was 27±3 ms. Spark frequency was 0.88 sparks µm−1 min−1 while calcium waves were 8.5 times less frequent. Inhibition of SR calcium uptake reduced the calcium transient (F/F0) from 1.77±0.17 to 1.12±0.18 (p = 0.002) and abolished calcium sparks and waves. Moreover, elevation of extracellular calcium from 2 to 10 mM promoted early and delayed afterdepolarizations (from 0.6±0.3 min−1 to 8.1±2.0 min−1, p = 0.001), demonstrating the ability of SR calcium release to induce afterdepolarizations in the trout heart. Calcium sparks of similar width and duration were also observed in zebrafish ventricular myocytes. In conclusion, this is the first study to consistently report calcium sparks in teleosts and demonstrate that the basic features of calcium release through the ryanodine receptor are conserved, suggesting that teleost cardiac myocytes is a relevant model to study the functional impact of abnormal SR function

Adverse effects from multi-drug therapy in leprosy: a Brazilian study.

INTRODUCTION: The WHO MDT for leprosy treatment was officially introduced in Brazil in 1991 and comprises three drugs: dapsone, rifampicin and clofazimine. There are few good studies on the frequency of side-effects attributable to MDT in Brazil. METHODS: A retrospective and descriptive study carried out in a LCP in Vitória, State of Espirito Santo, Brazil. A specific and detailed protocol about side-effects was prepared and filled in from the patient records. RESULTS: One hundred ninety four patients' records were analysed looking for side-effects attributable to MDT. Side-effects were attributed to at least one MDT component in 88 (45%) patients and 85 had side-effects due to dapsone, 24 due to rifampicin and 18 due to clofazimine. 185 episodes were identified. The suspected drug was stopped in 47 out of 88 episodes (24% patients); 46 had dapsone stopped, 5 had rifampicin stopped and no-one had clofazimine stopped. CONCLUSION: Side-effects attributed to MDT is more frequent than previously described, resulting in interruption of treatment in many patients