Intracellular Ca++/Mg++ homeostasis during postnatal growth of experimental rats. Multiple time-point study.
In most tissues, various cell membrane ion transporting systems are not fully developed and/or maximally active at the prenatal and early postnatal stage. Their progressive development and expression are a function of growth and maturity. We performed a multiple time-point study, in order to investigate the ability of a variety of tissues to maintain appropriate Ca++ and Mg++ homeostasis at different stages of postnatal development. Total intracellular Ca++ in one-week-old rat liver, brain and spinal cord tissues was significantly elevated, compared to mature animals. It increased further through the first three weeks of gestation. Intracellular Ca++ gradually and significantly declined in adult and mature animal groups. Alterations in total intracellular Mg++ of the same tissue samples, although not so profound, paralleled changes in total intracellular Ca++. We conclude that a developmental switch in intracellular Ca++ and Mg++ homeostasis occurs one to three weeks following birth. It might be related to the incomplete development of Ca++ and Mg++ transmembrane transporting systems, previously reported as being only partially expressed at the early postnatal stage. These developmental alterations in total intracellular Ca++ and Mg++ content might serve as a regulatory mechanism, adjusting cell activities to the physiological requirements of the growing and maturing animal.
Bahar
M
M
Department of Anesthesiology, Assaf Harofeh Medical Center, Zerifin 70300, Israel. anesthesia@asaf.health.gov.il
Berman
S
S
Grinshpon
Y
Y
Weissgarten
J
J
Averbukh
Z
Z
Cohen
M
M
Chanimov
M
M
D000818:Animals; D001921:Brain / Q000254:growth & development / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D005260:Female; D006128:Growth / Q000502:physiology*; D006706:Homeostasis; D007424:Intracellular Fluid / Q000378:metabolism; D017136:Ion Transport; D008099:Liver / Q000254:growth & development / Q000378:metabolism; D008274:Magnesium / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013116:Spinal Cord / Q000254:growth & development / Q000378:metabolism
D008274:Magnesium; D002118:Calcium