title: Novel function of the skin in calcium metabolism in female and male chickens (Gallus domesticus).
abstract: To study the role of the skin in differential calcium metabolism in White Leghorn chickens, we compared the composition of suction blister fluid (SBF) collected from cutaneous blisters with blood and serum in female and male animals in various physiological states. As an estimate for interstitial fluid (IF), SBF was used as a determinant of local cutaneous metabolism. Sample collection was carried out under ketamine-xylazine anesthesia. Eight chickens of both sexes were raised freely in similar environmental conditions and fed with similar food during their growth from juvenile to sexually mature and fully adult state. SBF, blood and serum were examined for concentrations of ionized Ca2+, Na+ and K+ with ion-selective electrodes (ISEs), and osmolalities by freezing point osmometry. pH and total protein content were also assessed. Our results showed that SBF of chickens is calcium-poor at the juvenile state and that it draws more Ca2+ in adult males than laying females of the same age. Interestingly, Ca2+ accumulation was observed also in females after laying had ceased. There was a positive correlation between blood and SBF Ca2+ in females but a negative one in males. In general, it was found that SBF of chickens was rich in Na+ and K+, was hypertonic compared to serum at the juvenile state and had a protein content of 36-47% of that in serum. Different from mammals, SBF in adult chickens was alkaline with the mean values of 8.7+/-0.14 in females and 8.8+/-0.06 in males. Age- and sex-related variability in cutaneous Ca2+ concentrations in chickens, and the differences of SBF composition between that of mammals point to a novel role of skin functions in avians. Possible functions of the skin as a dynamic calcium source balancing the free circulating Ca2+ levels and, also, as an excretory organ for Ca2+ are discussed.
authors.affiliation: Department of Biomedicine, Physiology, Biomedicum Helsinki, 00014 University of Helsinki, Finland. liisa.m.peltonen@helsinki.fi
authors.forename: Liisa M
authors.initials: LM
authors.lastname: Peltonen
authors.forename: Satu
authors.initials: S
authors.lastname: Sankari
authors.forename: Anneli
authors.initials: A
authors.lastname: Kivimäki
authors.forename: Pekka
authors.initials: P
authors.lastname: Autio
mesh_terms: D000375:Aging / Q000378:metabolism; D000818:Animals; D001826:Body Fluids / Q000737:chemistry; D002118:Calcium / Q000378:metabolism*; D002645:Chickens / Q000254:growth & development / Q000502:physiology*; D005260:Female; D006863:Hydrogen-Ion Concentration; D008297:Male; D009994:Osmolar Concentration; D011188:Potassium / Q000378:metabolism; D012737:Sex Factors; D012867:Skin / Q000378:metabolism; D012879:Skin Physiological Phenomena; D012964:Sodium / Q000378:metabolism
chemical_list: D012964:Sodium; D011188:Potassium; D002118:Calcium