title: The distribution and movements of carbon dioxide, carbonic acid and bicarbonate between blood and milk in the goat.
abstract: 1. A-V differences and milk concentrations of respiratory gases, pH, HCO3 and H2CO3 have been measured in lactating goats and cows. 2. The pH and [HCO3 minus] of milk were significantly lower than those of plasma while milk PCO2 was virtually identical to that of mammary venous blood. [H2CO3+ dissolved CO2] was similar in milk and blood. 3. 14-C (from injected [14-C]HCO3 minus was found to cross the mammary epithelium in both directions. 14-C also passed across the duct epithelium and since this epithelium has previously been shown to be impermeable to ions it is argued that 14-C crossed in an unionized form, i.e. as CO2 and/or H2CO3. 4. Hourly milking with the aid of oxytocin raised milk pH, [HCO3 minus], [H2CO3], [Na] and E1Cl], and lowered [K], [lactose] and [phosphate]. These effects are discussed in relation to the hypothesis proposed previously for the action of oxytocin on milk composition. 5. A scheme for the distribution and movements of CO2, H2CO3 and HCO3 minus between extracellular fluid and milk is suggested, and discussed in relation to Cl minus transport.
mesh_terms: D000818:Animals; D001639:Bicarbonates / Q000032:analysis / Q000097:blood / Q000378:metabolism*; D002245:Carbon Dioxide / Q000032:analysis / Q000097:blood / Q000378:metabolism*; D002250:Carbon Radioisotopes; D002254:Carbonates / Q000378:metabolism*; D002255:Carbonic Acid / Q000032:analysis / Q000097:blood / Q000378:metabolism*; D002417:Cattle; D002712:Chlorides / Q000378:metabolism; D004848:Epithelium / Q000378:metabolism; D005110:Extracellular Space / Q000378:metabolism; D005260:Female; D006041:Goats; D006863:Hydrogen-Ion Concentration; D007785:Lactose / Q000378:metabolism; D008026:Ligation; D008321:Mammary Glands, Animal / Q000378:metabolism; D008892:Milk / Q000032:analysis / Q000378:metabolism*; D010121:Oxytocin / Q000494:pharmacology; D010710:Phosphates / Q000378:metabolism; D011188:Potassium / Q000378:metabolism; D011247:Pregnancy; D012964:Sodium / Q000378:metabolism
chemical_list: D001639:Bicarbonates; D002250:Carbon Radioisotopes; D002254:Carbonates; D002712:Chlorides; D010710:Phosphates; D002245:Carbon Dioxide; D002255:Carbonic Acid; D010121:Oxytocin; D012964:Sodium; D007785:Lactose; D011188:Potassium