TY - JOUR
T1 - Hormonal and nutritional substrate control of cardiac lysosomal enzyme activities
AU - Wildenthal, K.
PY - 1976
Y1 - 1976
N2 - Prolonged starvation is known to induce significant alterations in several cardiac lysosomal enzymes, particularly the acid proteinase cathepsin D. To determine what specific factors might mediate these changes, fetal mouse hearts in organ culture were maintained in media designed to simulate selected hormonal or nutritional substrate changes that accompany starvation. Reduced concentrations of glucose caused an increase in the activity of β acetylglucosaminidase but had no effect on cathepsin D or acid phosphatase activities (i.e., effects opposite from those of starvation). Also, high concentrations of free fatty acid, acetoacetate, and β OH butyrate induced an increase in cathepsin D (+18%) and a simultaneous decrease in glucosaminidase (-19%), with little change in acid phosphatase. Furthermore, glucagon had no effect on any of the enzymes, whereas growth hormone caused a small (6%) increase in cathepsin D activity. In addition, insulin deprivation caused significant increases (7-25%) in the activities of all three enzymes. Insulin deprivation and excess ketones, but not the other interventions, increased the proportion of enzyme activity which was nonsedimentable. These results suggest the possibility that lysosomal alterations during starvation may be related in part to prolonged insulin deficiency and exposure to high concentrations of ketones and free fatty acids.
AB - Prolonged starvation is known to induce significant alterations in several cardiac lysosomal enzymes, particularly the acid proteinase cathepsin D. To determine what specific factors might mediate these changes, fetal mouse hearts in organ culture were maintained in media designed to simulate selected hormonal or nutritional substrate changes that accompany starvation. Reduced concentrations of glucose caused an increase in the activity of β acetylglucosaminidase but had no effect on cathepsin D or acid phosphatase activities (i.e., effects opposite from those of starvation). Also, high concentrations of free fatty acid, acetoacetate, and β OH butyrate induced an increase in cathepsin D (+18%) and a simultaneous decrease in glucosaminidase (-19%), with little change in acid phosphatase. Furthermore, glucagon had no effect on any of the enzymes, whereas growth hormone caused a small (6%) increase in cathepsin D activity. In addition, insulin deprivation caused significant increases (7-25%) in the activities of all three enzymes. Insulin deprivation and excess ketones, but not the other interventions, increased the proportion of enzyme activity which was nonsedimentable. These results suggest the possibility that lysosomal alterations during starvation may be related in part to prolonged insulin deficiency and exposure to high concentrations of ketones and free fatty acids.
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U2 - 10.1161/01.RES.39.3.441
DO - 10.1161/01.RES.39.3.441
M3 - Article
C2 - 954175
AN - SCOPUS:0017181825
SN - 0009-7330
VL - 39
SP - 441
EP - 446
JO - Circulation research
JF - Circulation research
IS - 3
ER -