ABSTRACT
[ABSTRACT]AIM:Toinvestigatetheeffectsofmechanicalstretchontransientoutwardpotassiumcurrent(Ito), inward rectifier potassium current ( IK1 ) and action potential duration ( APD) of cultured neonatal rat atrial myocytes . METHODS:Neonatal rat atrial myocytes were isolated and cultured on silicone sheeting with or without stretch for 24 h. The silicone membrane area was increased by 12%in stretched group.The cells without stretch served as control .Ito, IK1 and APD were recorded by the technique of whole-cell patch clamp.RESULTS:Compared with control group, Ito density in stretched myocytes was significantly reduced [(1.6 ±0.4) pA/pF vs (12.1 ±2.9) pA/pF, P<0.01], whereas IK1 density was increased [(-10.8 ±0.8) pA/pF vs (-8.8 ±0.9) pA/pF, P<0.01].The APDs at 50%and 90%levels of repolarization ( APD50 and APD90 ) in the stretched cells were obviously decreased than those in non-stretched cells [(10.5 ±1.4) ms vs (15.5 ±2.4) ms, (30.0 ±2.8) ms vs (56.3 ±3.6) ms, P<0.01].CONCLUSION: Stretch stimulation leads to the reduction of Ito density, the increase in IK1 density and the shortness of APD in cultured rat atrial neonatal myocytes , which may contribute to atrial electrical remodeling induced by pressure overload .
ABSTRACT
38 cases of Benign Monoclonal Gammopathy (BMG) representing 17.9% were screened from 212 cases of M-proteinemia by laboratory examinations. Among the 38 cases, 17 cases had increase of IgG, another 17 cases of IgA and 4 cases of IgM. Their average M-proteins were 1.42, 0.88 and 1.84 g/dl respectively.The salient points of differential of benign or malignant M-proteinemia were also discussed. The recommended sequential laboratory diagnostic procedure of BMG were as follows: tatol serum protein determination, plasma protein zone electrophresis, urine protein analysis, immunoglobulin quantitation and immunoelectrophresis or selective electrophresis.