Phasic changes in bone CO2 fractions, calcium, and phosphorus during chronic hypercapnia.
The bone CO2 buffering system and bone calcium and phosphorus were studied in guinea pigs exposed to 1% CO2 for periods up to 8 wk and killed at weekly intervals together with control animals of the same age. Measurements were made of arterial CO2 tension, pH, standard bicarbonate, and bone Ca and P. Heat-stabile bone CO2 (carbonate) was determined as dry bone CO2 and heat-labile bone CO2 (bicarbonate) as delta wet-dry bone CO2. During the first 3-4 wk of exposure to 1% CO2, a systemic acidosis was found as indicated in a lowered pH, increased arterial CO2 tension, and decreased standard bicarbonate. The acidosis subsided during the last 4 wk of exposure. Phasic changes in bone bicarbonate were observed as shown in immediate rise lasting for 2 wk followed by a 2-wk decline and second rise after 6 and 8 wk. Bone carbonate exhibited the opposite change during the first 4 wk and thereafter remained stable at an elevated level. Bone Ca and P fell in association with increasing bone bicarbonate and rose with increasing bone carbonate.
D000137:Acid-Base Imbalance / Q000378:metabolism; D000818:Animals; D001639:Bicarbonates / Q000378:metabolism; D001835:Body Weight; D001842:Bone and Bones / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D002245:Carbon Dioxide / Q000378:metabolism; D006168:Guinea Pigs; D006935:Hypercapnia / Q000378:metabolism*; D010758:Phosphorus / Q000378:metabolism*
D001639:Bicarbonates; D002245:Carbon Dioxide; D010758:Phosphorus; D002118:Calcium