Insulin sensitivity and calcium homeostasis in young, lean, normotensive male subjects.
Insulin resistance is known to be closely related to essential hypertension. It has been hypothesized that abnormal calcium homeostasis both at the cellular level and in the whole body plays a substantial role in hypertension associated with insulin resistance. We attempted to determine the relationships among insulin sensitivity, blood pressure (BP), body mass index (BMI), and calcium-related parameters in young, lean, normotensive male subjects with extreme susceptibilities to hypertension, and to investigate the effects of euglycemic hyperinsulinemia on calcium-related parameters. Seven young, lean, normotensive male subjects with family histories of essential hypertension and 10 age-matched controls without any parental cardiovascular events were enrolled. Insulin sensitivity measurement by the euglycemic hyperinsulinemic clamp technique and a 75-g oral glucose tolerance test were performed. Calcium-related parameters, including intracellular Ca2+ levels in platelets, were measured simultaneously. Diastolic BP was inversely correlated with insulin sensitivity in vivo (M-value). Insulin sensitivity was inversely correlated with BMI and with intracellular Ca2+ in platelets. In the multivariate stepwise regression analysis using both diastolic BP and insulin sensitivity as dependent variables, BMI was found to be a determinant independent variable. Euglycemic hyperinsulinemia decreased intact parathyroid hormone levels and increased fractional excretion of calcium. In conclusion, BMI rather than a family history of hypertension plays a determinant role on the regulation of diastolic BP and insulin sensitivity even in young, lean, normotensive male subjects with extreme predispositions for the development of hypertension. Hyperinsulinemia decreased intact parathyroid hormone levels and increased fractional excretion of calcium.
Ohno
Y
Y
Department of Internal Medicine, TEPCO Hospital, Tokyo, Japan.
Suzuki
H
H
Yamakawa
H
H
Nakamura
M
M
Saruta
T
T
D000328:Adult; D000367:Age Factors; D001786:Blood Glucose / Q000378:metabolism; D001792:Blood Platelets / Q000378:metabolism; D001794:Blood Pressure / Q000502:physiology*; D015992:Body Mass Index; D001835:Body Weight / Q000502:physiology*; D002118:Calcium / Q000378:metabolism*; D005192:Family Health; D020022:Genetic Predisposition to Disease; D015309:Glucose Clamp Technique; D005951:Glucose Tolerance Test; D006706:Homeostasis / Q000502:physiology*; D006801:Humans; D006946:Hyperinsulinism / Q000235:genetics / Q000378:metabolism; D006973:Hypertension / Q000235:genetics / Q000378:metabolism*; D007333:Insulin Resistance / Q000502:physiology*; D008297:Male; D012044:Regression Analysis
D001786:Blood Glucose; D002118:Calcium