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cAMP-dependent protein kinase-catalyzed phosphorylation of cardiac microsomes; relationship to calcium uptake
ABSTRACTS
EVALUATION OF A ONE-YEAR GRADUATED EXERCISE PROGRAM FOR MEN WITH ANGINA PECTORIS BY PHYSIOLOGIC STUDIES AND CORONARY ARTERIOGRAPHY Charles C. Kennedy, MD; Ralph E. Spiekerman, MD; Malcolm I. Lindsay, Jr., MD; Robert L. Frye, MD, FACC; Harold T. Mankin, MD, Mayo Clinic, Rochester, Minnesota; John D. Cantwell, MD, Atlanta, Ga.; Norris B. Harbold,Jr. MD, Charlotte, N.C. To assess the effect of a long-term exercise program on exercise tolerance, left ventricular (LV) hemodynamics, coronary collateral circulation (CCC) and psychodynamics, 8 men ages 45-52 with stable angina pectoris were evaluated prior to and on completion of a l-year graduated exercise program. This consisted of a complete physical examination, appropriate laboratory tests, treadmill testing (TT) with electrocardiographic (ECG) monitoring, measurements of oxygen u take (VO2) and cardiac catheterization for study of Le hemodynamics and coronary arteriography. At 3-month intervals, TT and VO2 were obtained. Exercise sessions held 3 times each week emphasized graduated sustained effort exercises working towards a 7585% maximal pulse rate. 5 of the 8 p.atients had a definite increase in exercise tolerance. V02 (-130 cc to 855 cc) decreased while measured at a specified work level on the treadmill. 2 had no change and 1 had an increase (fro.2 increasing 250 cc). These 3 had a positive correlation with less regular attendance. LV end diastolic pressure (LVEDP) increased in 7 patients from a mean of 16 mm Hg to 20 mm Hg. LVEDP decreased from 19 mm Hg to 15 mm Hg in 1 patient. The car iac index i creased in all ptients from a mean of 3.9 L/M 9 to 4.4 L/Ms . Mean arterial pressure decreased from 105 mm Hg to 102 mm Hg. No increase in CCC was noted. 3 of 6 patients with abnormal stress ECG's had a decrease in magnitude of ischemic change during the year. All experienced a decrease in angina, an increase in self-esteem and developed a more positive attitude towards their work and disability.
PULMONARY ARTERY HYPERTENSION AFTER REPAIR OF TETRALOGY OF FALLOT Robin H. Kinsley, MD; Douglas D. Mair, MD; Gordon K. Danielson, MD, FACC; Robert B. Wallace, MD; Dwight C. McGoon, MD, Mayo Clinic and Mayo Foundation, Rochester, Minnesota.
THE VENOCONSTRICTOR PROPERTIES OF ISOPROTERENOL: DEPENDENCE ON THE LEVEL OF ENDOGENOUS SYMPATHETIC TONE James King, MD; Dean T. Mason, MD. FACC; Ezra A. Amsterdam MD, FACC and Robert Zelis, MD, FACC, Dept. Med., Univ. Calif. Sch. Med., Davis, Ca.
CAMP-DEPENDENT PROTEIN KINASE-CATALYZED PHOSPHORYLATION OF CARDIAC MICROSOMES; RELATIONSHIP TO CALC.lUMUPTAKE Madeleine A. Kirchberger, PhD, Michihiko M. Tada, MD, PhD, Doris I. Repke, CT, Sylvia Yoshioka, BA, and Arnold M. Katz, MD, FACC, Mount Sinai School of Medicine of the City University of New York, New York, N.Y.
The frequent use of isoproterenol (ISO) for the augmentation of myocardial contractility in heart failure has prompted considerable investigation into the mechanism of its inotropic and circulatory effects. Although the arteriolar dilator capacity of IS0 is well documented, its effects on venous tone are unclear and may depend on endogenous sympathetic tone. Therefore, IS0 was infused intraarterially in nine normal volunteers and forearm blood flow (FBF) and venous volume (W[30]) was measured plethysmographically during body heating and cooling. FBF increased from 4.75 to 7.04 (p>.O5), 11.7 (p<.Ol), 14.38 (pc.01) and 20.44 (pc.01) ml/min/lOO ml with IS0 at .123, .247, .494 and 1.23 ug/min respectively with body heating, but only increased from 2.01 to 2.30 (p>.2), 3.41 (p>.O5), 5.66 (pc.02). 7.13 (pc.01) with IS0 during body cooling. Although this suggested that the resistance vessels were more sensitive to IS0 when dilated by thermal sympatholysis, the percent increase in FBF was not significantly different (p>.5). Basal W[30] was less during cooling (2.22 cc/100 cc) than heating (3.42 cc/100 cc, p<.O5), the lower VV[30] indicating a significant venoconstriction. When the subjects were warm, only the two higher dose levels of IS0 produced a constriction (AVV[30] -10.2% (~~~01); -14.7% (pc.01). During cooling a venoconstriction was seen at three upper levels of IS0 AW[30], -34.4% (p<.Ol), -32.8% (p<.Ol), -38.5% (pc.01) cc/100 cc. At each dose the venoconstriction with IS0 was significantly greater when the subject was cooled. Thus in acute heart failure where sympathetic tone is high, IS0 might be expected to significantly augment venous return.
Sixty-one of 1,000 patients undergoing complete repair of tetralogy were found to have pulmonary arterial hypertension (PA-50 rmn Hg or PAP/LVs.5) in the operating room after repair. Analysis of this experience showed that the prognostic significance of increased PAP depends on its cause, reversibility, and severity. Four deaths occurred in the 39 patients with major peripheral pulmonary arterial obstruction (group 1). Of 12 patients with Potts shunts (group 2), all 5 with severe arteriolar disease died. Five of 6 patients with a residual VSD (group 3) died. Mortality tended to be greater when PAP/LV was higher. Pulmonary annular hypoplasia and the need for patch reconstruction was usual in group 1 but exceptional in group 2. Repeat cardiac catheterization in 17 patients showed decreased PAP in 5 patients, due to either development of an RV-PA gradient or a return of pulmonary vascular resistance to normal. The sole survivor with a residual VSD developed severe pulmonary arteriolar disease within 2 years even after successful reoperation. Late results were good in groups 1 and 2 but tragic in group 3, indicating the necessity of ruling out residual VSD promptly whenever pulmonary hypertension exists after discontinuation of extracorporeal circulation.
We have recently demonstrated marked enhancement of cardiac microsomal (sarcoplasmic reticulum) Ca-uptake by a partially purified CAMP-dependent protein kinase (CAMP-PK). To relate enhanced Ca-uptake to CAMP-PKcatalyzed phosphorylation, dog heart microsomes (0.5 rug/ ml) were incubated at 300 in 2.5 mM Tris-oxalate, 0.1 M KCl, 7.5 x 10-T M Ca++ (Ca-EGTA buffer] and 40 mM histidine buffer, pH 6.8; also present were CAMP or CAMP-PK. After 5 min preincubation, 5 mM Mg-Y-32P-AlT was added to start the reaction. Reactions were stopped with 10% TCA + 1 mM KQF’O4, and labelled protein was washed and counted. Both rate and extent of phosphorylation were slightly increased by CAMP or CAMP-PK alone, but were increased 2 to h-fold by CAMP-PK in the presence of CAMP. Half-maximal stimulation of phosphorylation was observed at about 2 x 10-T M CAMP in the presence of CAMP-PK. Stimulation of phosphorylation by CAMP&K was most marked during the first 5 min. Phospho lation was inrK to 10-T M, dependent of Ca++ concentration from loand decreased slightly from 10-T to 10-6 M Ca++. The time course, CAMP dose-response, and response to Ca* of CAMP-PK-catalyzed microsome phosphorylation are similar to those observed for CAMP-PK stimulation of microsomal Ca-uptake. These studies thus support the view that CAMP-PK-catalyzed phosphorylation causes increased Ca-uptake by cardiac microsomes.
January 1973
The American Journal of CARDIOLOGY
Volume 31
141
EVALUATION OF A ONE-YEAR GRADUATED EXERCISE PROGRAM FOR MEN WITH ANGINA PECTORIS BY PHYSIOLOGIC STUDIES AND CORONARY ARTERIOGRAPHY Charles C. Kennedy, MD; Ralph E. Spiekerman, MD; Malcolm I. Lindsay, Jr., MD; Robert L. Frye, MD, FACC; Harold T. Mankin, MD, Mayo Clinic, Rochester, Minnesota; John D. Cantwell, MD, Atlanta, Ga.; Norris B. Harbold,Jr. MD, Charlotte, N.C. To assess the effect of a long-term exercise program on exercise tolerance, left ventricular (LV) hemodynamics, coronary collateral circulation (CCC) and psychodynamics, 8 men ages 45-52 with stable angina pectoris were evaluated prior to and on completion of a l-year graduated exercise program. This consisted of a complete physical examination, appropriate laboratory tests, treadmill testing (TT) with electrocardiographic (ECG) monitoring, measurements of oxygen u take (VO2) and cardiac catheterization for study of Le hemodynamics and coronary arteriography. At 3-month intervals, TT and VO2 were obtained. Exercise sessions held 3 times each week emphasized graduated sustained effort exercises working towards a 7585% maximal pulse rate. 5 of the 8 p.atients had a definite increase in exercise tolerance. V02 (-130 cc to 855 cc) decreased while measured at a specified work level on the treadmill. 2 had no change and 1 had an increase (fro.2 increasing 250 cc). These 3 had a positive correlation with less regular attendance. LV end diastolic pressure (LVEDP) increased in 7 patients from a mean of 16 mm Hg to 20 mm Hg. LVEDP decreased from 19 mm Hg to 15 mm Hg in 1 patient. The car iac index i creased in all ptients from a mean of 3.9 L/M 9 to 4.4 L/Ms . Mean arterial pressure decreased from 105 mm Hg to 102 mm Hg. No increase in CCC was noted. 3 of 6 patients with abnormal stress ECG's had a decrease in magnitude of ischemic change during the year. All experienced a decrease in angina, an increase in self-esteem and developed a more positive attitude towards their work and disability.
PULMONARY ARTERY HYPERTENSION AFTER REPAIR OF TETRALOGY OF FALLOT Robin H. Kinsley, MD; Douglas D. Mair, MD; Gordon K. Danielson, MD, FACC; Robert B. Wallace, MD; Dwight C. McGoon, MD, Mayo Clinic and Mayo Foundation, Rochester, Minnesota.
THE VENOCONSTRICTOR PROPERTIES OF ISOPROTERENOL: DEPENDENCE ON THE LEVEL OF ENDOGENOUS SYMPATHETIC TONE James King, MD; Dean T. Mason, MD. FACC; Ezra A. Amsterdam MD, FACC and Robert Zelis, MD, FACC, Dept. Med., Univ. Calif. Sch. Med., Davis, Ca.
CAMP-DEPENDENT PROTEIN KINASE-CATALYZED PHOSPHORYLATION OF CARDIAC MICROSOMES; RELATIONSHIP TO CALC.lUMUPTAKE Madeleine A. Kirchberger, PhD, Michihiko M. Tada, MD, PhD, Doris I. Repke, CT, Sylvia Yoshioka, BA, and Arnold M. Katz, MD, FACC, Mount Sinai School of Medicine of the City University of New York, New York, N.Y.
The frequent use of isoproterenol (ISO) for the augmentation of myocardial contractility in heart failure has prompted considerable investigation into the mechanism of its inotropic and circulatory effects. Although the arteriolar dilator capacity of IS0 is well documented, its effects on venous tone are unclear and may depend on endogenous sympathetic tone. Therefore, IS0 was infused intraarterially in nine normal volunteers and forearm blood flow (FBF) and venous volume (W[30]) was measured plethysmographically during body heating and cooling. FBF increased from 4.75 to 7.04 (p>.O5), 11.7 (p<.Ol), 14.38 (pc.01) and 20.44 (pc.01) ml/min/lOO ml with IS0 at .123, .247, .494 and 1.23 ug/min respectively with body heating, but only increased from 2.01 to 2.30 (p>.2), 3.41 (p>.O5), 5.66 (pc.02). 7.13 (pc.01) with IS0 during body cooling. Although this suggested that the resistance vessels were more sensitive to IS0 when dilated by thermal sympatholysis, the percent increase in FBF was not significantly different (p>.5). Basal W[30] was less during cooling (2.22 cc/100 cc) than heating (3.42 cc/100 cc, p<.O5), the lower VV[30] indicating a significant venoconstriction. When the subjects were warm, only the two higher dose levels of IS0 produced a constriction (AVV[30] -10.2% (~~~01); -14.7% (pc.01). During cooling a venoconstriction was seen at three upper levels of IS0 AW[30], -34.4% (p<.Ol), -32.8% (p<.Ol), -38.5% (pc.01) cc/100 cc. At each dose the venoconstriction with IS0 was significantly greater when the subject was cooled. Thus in acute heart failure where sympathetic tone is high, IS0 might be expected to significantly augment venous return.
Sixty-one of 1,000 patients undergoing complete repair of tetralogy were found to have pulmonary arterial hypertension (PA-50 rmn Hg or PAP/LVs.5) in the operating room after repair. Analysis of this experience showed that the prognostic significance of increased PAP depends on its cause, reversibility, and severity. Four deaths occurred in the 39 patients with major peripheral pulmonary arterial obstruction (group 1). Of 12 patients with Potts shunts (group 2), all 5 with severe arteriolar disease died. Five of 6 patients with a residual VSD (group 3) died. Mortality tended to be greater when PAP/LV was higher. Pulmonary annular hypoplasia and the need for patch reconstruction was usual in group 1 but exceptional in group 2. Repeat cardiac catheterization in 17 patients showed decreased PAP in 5 patients, due to either development of an RV-PA gradient or a return of pulmonary vascular resistance to normal. The sole survivor with a residual VSD developed severe pulmonary arteriolar disease within 2 years even after successful reoperation. Late results were good in groups 1 and 2 but tragic in group 3, indicating the necessity of ruling out residual VSD promptly whenever pulmonary hypertension exists after discontinuation of extracorporeal circulation.
We have recently demonstrated marked enhancement of cardiac microsomal (sarcoplasmic reticulum) Ca-uptake by a partially purified CAMP-dependent protein kinase (CAMP-PK). To relate enhanced Ca-uptake to CAMP-PKcatalyzed phosphorylation, dog heart microsomes (0.5 rug/ ml) were incubated at 300 in 2.5 mM Tris-oxalate, 0.1 M KCl, 7.5 x 10-T M Ca++ (Ca-EGTA buffer] and 40 mM histidine buffer, pH 6.8; also present were CAMP or CAMP-PK. After 5 min preincubation, 5 mM Mg-Y-32P-AlT was added to start the reaction. Reactions were stopped with 10% TCA + 1 mM KQF’O4, and labelled protein was washed and counted. Both rate and extent of phosphorylation were slightly increased by CAMP or CAMP-PK alone, but were increased 2 to h-fold by CAMP-PK in the presence of CAMP. Half-maximal stimulation of phosphorylation was observed at about 2 x 10-T M CAMP in the presence of CAMP-PK. Stimulation of phosphorylation by CAMP&K was most marked during the first 5 min. Phospho lation was inrK to 10-T M, dependent of Ca++ concentration from loand decreased slightly from 10-T to 10-6 M Ca++. The time course, CAMP dose-response, and response to Ca* of CAMP-PK-catalyzed microsome phosphorylation are similar to those observed for CAMP-PK stimulation of microsomal Ca-uptake. These studies thus support the view that CAMP-PK-catalyzed phosphorylation causes increased Ca-uptake by cardiac microsomes.
January 1973
The American Journal of CARDIOLOGY
Volume 31
141