KINETICS OF STEROID EFFECTS OF Ca$sup 47$ DYNAMICS IN DOGS WITH THE ANALOG COMPUTER. PART I
A detailed quantitative analysis is presented of the effects of adrenal steroids on the distribution and kinetics of intravenously administered Ca/sup 47/ in dogs. The digitaland analog-computer techniques described herein facilitated quantifications of the massive data. The initial disappearance curves of radiocalcium from the blood were also determined. Four polyexponentials were used to describe the Ca/sup 47/ content of blood as a function of time after intravenous administration, Quantitative measures of determining Ca/sup 47/ incorporation into the deep compartment that may be synonymous with bone are described. The exponential constants for the distribution and elimination of Ca/ sup 47/ for all dogs and under all conditions studied (control, steroid, and recovery periods) were similar. The short half life of Ca/sup 47/ of 4.56 days permitted sequence studies of Ca dynamics from the distribution and excretion of Ca/sup 47/ The most pronounced effect of steroid (6 alpha -methylprednisolone) treatment in dogs was the increased amount of Ca/sup 47/ accumulated in the feces. A similar effect was observed with Ca/sup 47/ accumulated in the urine although the percentage of the total administered dose excreted in the urine (2 to 6%) was much less than that excreted in the feces (20 to 60%). A possible, but less well- defined effect of steroid treatment was the decrease in apparent blood volume from the control period as based on measurement of Ca/sup 47/ in blood. The rate of Ca/sup 47/ return from the deep compartment was accelerated by steroid therapy. It may be that bone accretion is inhibited and bone resorption accelerated by steroid therapy, inducing the reversible osteoporosis seen by Cushing' s syndrome. A rebound effect was also noted in that, on cessation of steroid therapy, the dog utilizes more Ca/sup 47/ and the rate of return from the deep compartment is lessened. The possible utilization of more effective osteoporotic agents as measured by these techniques is of interest in the removal of bone-seeking radioisotopes produced by fallout contamination. (BBB)
- Research Organization:
- Univ. of Florida, Gainesville
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-18-015795
- OSTI ID:
- 4075114
- Journal Information:
- Journal of Pharmaceutical Sciences (U.S.), Journal Name: Journal of Pharmaceutical Sciences (U.S.) Vol. Vol: 51; ISSN JPMSA
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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