BETA-ENDORPHIN-LIKE AND ADRENOCORTICOTROPIN-LIKE MATERIALS IN HEART TISSUES OF THE RAT, GERBIL, HAMSTER AND GUINEA-PIG

1. 1. Heart tissues of several rodent species including the rat, gerbil (Meriones unguiculatus), hamster (Mesocricetus auratus) and guinea pig (Cavia porcellus) were extracted with an acetone-water-HC1 mixture. An acid acetone powder was obtained by adding a copious volume of acetone to the extract. 2. 2. Rat heart acid acetone powder was subjected to ion exchange chromatography on CM-cellulose. Gerbil heart acid acetone powder was subjected to salt fractionation, gel filtration on Sephadex G-10 and then ion exchange chromatography on CM-cellulose. Hamster and guinea pig heart acid acetone powders were subjected to gel filtration on Sephadex G-25. 3. 3. The fractions were assayed for the ability to stimulate corticosterone production in isolated rat adrenal decapsular (zona fasciculata, zona reticularis and medulla) cells, to displace D-ala2-D-leu5-(tyrosyl-3,5-3H) enkephalin from binding to rat brain membranes, and to inhibit 125I-human β-endorphin from binding to its antibodies. 4. 4. The widespread occurrence of β-endorphin-like immunoreactivity among the rat heart CM-cellulose fractions may reflect different species of β-endorphin. The fraction with the highest β-endorphin-like immunoreactivity and opiate receptor binding activity was strongly adsorbed on CM-cellulose. 5. 5. In hamster and guinea pig hearts, β-endorphin-like immunoreactivity and opiate receptor binding activity were distributed among high molecular weight and low molecular weight fractions. 6. 6. In gerbil hearts, opiate receptor binding activity was present in fractions unretarded on Sephadex G-10 (i.e. with a molecular weight greater than 700) as well as in the retarded fractions (i.e. with a molecular weight smaller than 700). 7. 7. Steroidogenic activity resided in both high and low molecular weight fractions in hamster and guinea pig hearts. In rat hearts the majority of Steroidogenic activity was adsorbed on CM-cellulose. In gerbil hearts Steroidogenic activity was also present. © 1990.