Serum isoforms of bone alkaline phosphatase increase during physical exercise in women.

Physical activity is an important factor for maintaining and probably increasing bone mass in humans. However, the mechanism by which this takes place is not completely understood. The purpose of this study was to examine the influence of physical exercise on serum alkaline phosphatase (ALP) and in particular, the bone isoforms of ALP.

Vasoactive intestinal polypeptide stimulates parathyroid hormone release by interaction with cyclic adenosine monophosphate production of bovine parathyroid cells.

Influence of vasoactive intestinal polypeptide, neuropeptide Y, calcitonin gene-related peptide, and substance P was investigated on dispersed parathyroid cells of adult cattle. At a physiological concentration of extracellular calcium, vasoactive intestinal polypeptide stimulated the parathyroid hormone release in a dose-dependent manner, whereas no effects were noted for the other peptides. The dependency of PTH secretion upon extracellular calcium was shifted to the right by vasoactive intestinal polypeptide at 10(-6) mol/l, with a tendency for greater effects at low (0.

Platelet and plasma catecholamines in relation to plasma minerals and parathyroid hormone following acute myocardial infarction.

Epinephrine has been shown to lower the plasma concentrations of several minerals and elevate those of parathyroid hormone (PTH). In order to evaluate the possible clinical importance of such experimental observations, 34 patients with acute myocardial infarction (AMI) were studied with daily determinations of plasma catecholamines, minerals, and PTH during the first week after AMI and at follow-up one month later. In addition, platelet catecholamines were determined as they fluctuate more slowly than plasma catecholamines.

Effects of prolonged adrenaline infusion and of mental stress on plasma minerals and parathyroid hormone.

The role of the sympatho-adrenal system for the secretion of PTH in humans is not established. Previous studies on the effects of adrenaline on plasma mineral homeostasis have focused on injections or short-term infusions of adrenaline, and conflicting results concerning calcium and parathyroid hormone (PTH) responses have been reported. We therefore infused adrenaline or placebo continuously for 3 h to 10 healthy volunteers and studied several plasma minerals, as well as PTH levels.

Serum electrolytes and parathyroid hormone in patients in a coronary care unit.

A prospective study was carried out in 499 patients admitted to a coronary care unit (CCU) in order to evaluate the incidence of clinically significant electrolyte disturbances. Low serum potassium values (less than 3.6 mmol l) occurred in 7% of the CCU patients and low serum magnesium values (less than 0.

Increase in serum parathyroid hormone levels after prolonged physical exercise.

Serum concentrations of parathyroid hormone (PTH), calcium, magnesium, phosphate and myoglobin were measured regularly during a 5-d recovery period in 17 men who had participated in a 7-d field exercise maneuver with intense physical activity. Immediately after the exercise, there was an increase in serum PTH levels of the same magnitude as the maximal rise during a hypocalcemic test. The rise in PTH was not related to changes in serum electrolytes, but was significantly correlated to an increase in serum myoglobin, indicating that those who performed the largest amount of work also experienced the greatest stimulus for secretion of PTH.

Effects of propranolol and verapamil on plasma ionized calcium and parathyroid hormone in short-term intense isokinetic leg exercise.

Physical exercise, beta-adrenergic stimulation and calcium channel blockade can affect calcium homeostasis. The present study investigated, in eight healthy males, the effects of orally administered propranolol or verapamil during a 2-min maximal, isokinetic, leg exercise. Immediately after exercise the plasma ionized calcium concentrations were increased, in control and drug tests, by 5-6%, and within 5 min of recovery they were almost returned to baseline.

Maximal isokinetic muscle strength in patients with primary hyperparathyroidism before and after parathyroid surgery.

Primary hyperparathyroidism (HPT) is associated with symptoms of generalized fatigue and muscle weakness. The purpose of this study was to investigate muscular function in HPT quantitatively and to evaluate the effect of parathyroid surgery in this respect. The maximal isokinetic muscle strength (peak torque) of knee extension and flexion was measured with a Cybex-II dynamometer in 16 patients with primary HPT (mean serum calcium 2.

Reduction of serum parathyroid hormone levels during sympathetic stimulation in man.

The parathyroid glands contain sympathetic nerve endings and the parathyroid cells are endowed with beta-adrenergic receptors. The physiological role of the sympathoadrenal system for the secretion of parathyroid hormone (PTH) has, however, not been clarified. Using the technique of lower body negative pressure (LBNP), which is an established method to achieve sympathetic nerve activation, it was found in 17 healthy subjects that the venous serum levels of PTH were reduced by 7% within 20 min [from 0.

Plasma potassium and phosphate concentrations--influence by adrenaline infusion, beta-blockade and physical exercise.

Infusion of adrenaline into healthy male subjects reduced the plasma concentrations of both potassium and phosphate to a similar extent, in a dose-dependent manner, an effect which was prevented by the administration of propranolol. Ergometer bicycling until exhaustion, which caused marked accumulation of lactic acid in the blood and reduction of pH, induced great elevations of both plasma potassium and phosphate with close relationships between the raised plasma concentrations and the reduction in pH, also during beta-blockade. However, longer-term aerobic exercise, without acidosis, also caused some rise of the potassium and phosphate concentrations.

Serum electrolytes and parathyroid hormone concentrations in acute myocardial infarction.

Serum concentrations of calcium, magnesium, potassium and phosphate can be lowered experimentally by adrenaline, which also can stimulate the secretion of parathyroid hormone (PTH). In order to evaluate the possible clinical importance of these mechanisms serial blood samples were drawn during the first three hospital days in 26 patients with acute myocardial infarction (AMI), a condition known to increase plasma catecholamine levels. During the study period there were no consistent significant changes of the serum electrolytes.

Prolonged low-intensity exercise raises the serum parathyroid hormone levels.

Twelve healthy males performed 5 h exercise on a bicycle ergometer at a constant work load of approximately 50% of their maximum capacity. The serum concentrations of parathyroid hormone (PTH) increased after the first hour and were continuously elevated throughout the exercise period. The rise in PTH was 5-7% above pre-exercise levels, corresponding to 20-30% of the maximal increase obtained by the same assay during prolonged hypocalcaemia.

Regional and systemic effects of short-term intense muscular work on plasma concentration and content of total and ionized calcium.

Isokinetic work with one leg was carried out with maximal force for 2 min by five healthy subjects. The concentrations of plasma total calcium and of ionized calcium in the effluent from the leg increased by a mean of 13.6 +/- 1.

Effects of exogenous catecholamines and exercise on plasma magnesium concentrations.

Catecholamines and physical exercise are known to influence the metabolism of several minerals in man, but the effects on magnesium (Mg) have been scarcely investigated. In the present study, infusion of adrenaline (5 micrograms/min for 30 min followed by 10 micrograms/min for 30 minutes) significantly reduced the plasma Mg levels in healthy males. This effect was abolished by simultaneous infusion of propranolol.

Effects of physical exercise on serum calcium and parathyroid hormone.

The effects of physical exercise on plasma ionized calcium, total serum calcium and parathyroid hormone (PTH) concentrations were evaluated in healthy subjects submitted to work on an ergometer bicycle. When the workload was increased stepwise there was a significant increase (P less than 0.001) in the calcium concentrations (ionized calcium from 1.