The Relationship of Pulmonary Artery Copper Concentrations and Genes Involved in Copper Homeostasis in Cattle, Swine, and Goats

Liver and pulmonary artery tissue from 5 Angus cross bred steers, 6 goats, and 6 pigs were collected at a commercial abattoir to examine the relationship of pulmonary artery copper (Cu) concentrations and genes involved in copper homeostasis. Liver and pulmonary artery samples were collected at the time of harvest and snap frozen. Liver and pulmonary artery Cu concentrations were determined via flame atomic absorption spectrophotometry and gene expression was determined via real time PCR. Liver Cu concentrations (mg Cu/kg DM${\pm}$SE) were higher (p<0.01) in cows ($396.4{\pm}109.1$) and goats ($181.4{\pm}37.0$) than in pigs ($19.2{\pm}3.5$). All liver Cu concentrations were within normal ranges and considered adequate for each species. Liver Cu concentration was more variable in cows and goats compared to pig liver Cu concentrations. Pulmonary artery ${\beta}$-hydroxylproline was higher (p<0.01) in cow and pig than goat. Real Time PCR revealed that goat liver atp7a was positively correlated ($r^2$ = 0.92; p<0.01) to liver Cu concentrations while cow and pig atp7a was not correlated to liver Cu concentration. In the pig, liver atp7a concentration was positively correlated to atp7b ($r^2$ = 0.66; p<0.05). Pulmonary artery Cu concentration was highest in cows ($14.9{\pm}4.7$), intermediate in pigs ($8.9{\pm}3.3$), and lowest in goats ($3.9{\pm}1.1$). Goat pulmonary artery Cu concentration was not correlated to ctr1 concentration, however, atp7a concentration was positively correlated with ctr1 ($r^2$ = 0.90; p<0.01). In cow pulmonary artery, loxl1 concentration was positively correlated to eln mRNA concentration ($r^2$ = 0.91; p<0.02). Pulmonary artery CTR1 protein concentration was positively correlated to pulmonary artery Cu ($r^2$ = 0.85; p = 0.03) concentration while negatively correlated to liver Cu ($r^2$ = -0.79; p<0.04). Pulmonary artery Cu concentration was not correlated to concentration of Cu homeostatic genes in the pig. These data indicate that genes involved in Cu homeostasis (ctr1, atp7A, atp7B, loxl1 and eln) are differently regulated in different species.