Changes in blood catecholamine levels in neonatal and growing lambs.

Changes in the palsma catecholamine (A and NA) and FFA concentrations were followed in 12 lambs from birth to 6 months of age. At birth plasma A, NA and FFA levels were higher than those at 6 months of age. Within first 3 days of life plasma A concentration markedly increased, and that of NA decreased, but on the 10th day of age both catecholamines returned to the levels found after first suckling. At this time significant decline in plasma FFA level occured. Later on up to 100 days blood A did not change, whereas NA stabilized on a relatively high level, which resulted in a marked increase of total catecholamine concentration and in a high NA/A ratio. The weaning stress caused a marked increase in blood total catecholamine and FFA levels. No relationship between plasma catecholamine and FFA levels was found during the whole period of growth considered.