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Intravenous magnesium in the treatment of tachyarrhythmias
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ON THE SUBCELLULAR DISTRIBUTION OF PARTICULATE GUANYLATE CYCLASE IN CARDIAC MUSCLE. E.-G. Krause. P.Karczewski, H.-L Misselwitz. H. Will and A. Wollenberner. Central Institute af Heart and Circulatory Regulation Research, Academy of Sciences of the DDR, Berlin-Buch, German Democratic Republic In cardiac muscle the greater part of guanylate cyclase (GC) is particle-bound, but the precise aubcellular localization of particulate activity has not yet been determined. To study the subcellular dietribution of this enzyme in cardiac muscle highly purified fractions of sarcoplaamic reticulum (SR) and saroolemma (SL) were prepared according to Levitaky et al. (BBA 443,467,1976) and Misselwitz et al. (Abstr. 12th FEBS Meet. 1978, in preea) from pigeon heart by successive rate zonal and Faopycnic centrifugation of conventional microaomea partially loaded with calcium oxalate. A very high GC activity, amounting to 0.67 nmolea/mg protein x min at 37OC, was found to be present in the SR fraction. The corresponding value for the SL fraction was 0.25 nmoles. Adenylate cyclase (AC) activity in SR and SL amounted to 0.04 and 0.54 nmolea/ng protein x min, yielding GC/AC ra.tios of 17 for SR and 0.4 for SL. The association of high GC activity with the Ca 5 + sequeatring SR vesicles seems of particular interest in the light of the concept (Schultz et al. 1973) that Ca2+ may be the moat important effector of CC.
A. Kumar, INTRAVENOUS MAGNESIUM IN THE TREATMENT OF TACHYARRHYTHMIAS. G.M. & M. Hasan, R.C. Ahuja, N.N. Gupta, P.C. Bajpai and T.D. Seth. K.G.‘s Medical College, Lucknow, India. Associated Hospitals, 25 cases with 29 episodes of cardiac tachyarrhythmias of varied aetiology were given slow intravenous magnesium sulphate in a dose of 20 Pretreatment serum cc of 20% solution under continuous ECG monitoring. magnesium levels were determined in all cases of atomic absorption An overall favourable response to magnesium was spectrophotometer. No response was obtained in obtained in 68.9% of the tachyarrhythmias. all the 6 cases of chronic atria1 fibrillation due to underlying chronic The response was significantly better in reheumatic heart disease. ventricular tachyarrhythmias as compared to supraventricular (X2 0.05). 100% of digitalis induced tachyarrhythmias and 66.7% of non-digitalis thereby showing that magnesium was induced tachyarrhythmias responded, The response also effective in non-digitalis induced tachyarrhythmias. was unrelated to the underlying aetiology of the heart disease and the Magnesium is therefore valuable as an antiarrserum magnesium level. hythmic drug.
ON THE SUBCELLULAR DISTRIBUTION OF PARTICULATE GUANYLATE CYCLASE IN CARDIAC MUSCLE. E.-G. Krause. P.Karczewski, H.-L Misselwitz. H. Will and A. Wollenberner. Central Institute af Heart and Circulatory Regulation Research, Academy of Sciences of the DDR, Berlin-Buch, German Democratic Republic In cardiac muscle the greater part of guanylate cyclase (GC) is particle-bound, but the precise aubcellular localization of particulate activity has not yet been determined. To study the subcellular dietribution of this enzyme in cardiac muscle highly purified fractions of sarcoplaamic reticulum (SR) and saroolemma (SL) were prepared according to Levitaky et al. (BBA 443,467,1976) and Misselwitz et al. (Abstr. 12th FEBS Meet. 1978, in preea) from pigeon heart by successive rate zonal and Faopycnic centrifugation of conventional microaomea partially loaded with calcium oxalate. A very high GC activity, amounting to 0.67 nmolea/mg protein x min at 37OC, was found to be present in the SR fraction. The corresponding value for the SL fraction was 0.25 nmoles. Adenylate cyclase (AC) activity in SR and SL amounted to 0.04 and 0.54 nmolea/ng protein x min, yielding GC/AC ra.tios of 17 for SR and 0.4 for SL. The association of high GC activity with the Ca 5 + sequeatring SR vesicles seems of particular interest in the light of the concept (Schultz et al. 1973) that Ca2+ may be the moat important effector of CC.
A. Kumar, INTRAVENOUS MAGNESIUM IN THE TREATMENT OF TACHYARRHYTHMIAS. G.M. & M. Hasan, R.C. Ahuja, N.N. Gupta, P.C. Bajpai and T.D. Seth. K.G.‘s Medical College, Lucknow, India. Associated Hospitals, 25 cases with 29 episodes of cardiac tachyarrhythmias of varied aetiology were given slow intravenous magnesium sulphate in a dose of 20 Pretreatment serum cc of 20% solution under continuous ECG monitoring. magnesium levels were determined in all cases of atomic absorption An overall favourable response to magnesium was spectrophotometer. No response was obtained in obtained in 68.9% of the tachyarrhythmias. all the 6 cases of chronic atria1 fibrillation due to underlying chronic The response was significantly better in reheumatic heart disease. ventricular tachyarrhythmias as compared to supraventricular (X2 0.05). 100% of digitalis induced tachyarrhythmias and 66.7% of non-digitalis thereby showing that magnesium was induced tachyarrhythmias responded, The response also effective in non-digitalis induced tachyarrhythmias. was unrelated to the underlying aetiology of the heart disease and the Magnesium is therefore valuable as an antiarrserum magnesium level. hythmic drug.