AJP - Heart and Circulatory Physiology, Vol 242, Issue 4 705-H712, Copyright © 1982 by American Physiological Society
Exchange of potassium and strontium in adult bone
B. Maltby, G. J. Lemon, J. B. Bassingthwaighte and P. J. Kelly
The kinetics of exchange of strontium (85Sr) and potassium (42K) were
studied in the mid-tibial cortical bone of 37 adult dogs. After injection
of these two tracer cations and tracer-labeled albumin into the tibial
nutrient artery, two types of observations were made: 1) collection of
sequential venous samples to provide the outflow indicator-dilution curves
and to calculate the extraction and retention at early times; and 2)
detection of energy-selected gamma emissions via a detector over the tibia
to give the time course of content of 42K and 85Sr in the tibia.
Extractions of K+ and Sr2+ were 50 and 60% during a single transcapillary
passage. More Sr2+ than K+ was retained in the first minutes. Their rates
of washout over a 3-h period were similar. The interpretation is that the
rate of uptake at extravascular sites is faster for Sr2+ than for K+, as is
the rate of release, and that the extravascular volume of distribution for
Sr2+ (adsorption sites in the interstitium or on bone) is much larger than
that for K+ (intracellular).
