MULTIPLE VASOACTIVE FACTORS IN EPIDERMAL SECRETIONS OF THE ARABIAN GULF CATFISH, ARIUS-BILINEATUS (VALENCIENNES)

1. The Arabian Gulf catfish produces proteinaceous epidermal secretion s when threatened or injured. 2. The soluble fraction of the catfish e pidermal secretions (SES) has vasoconstrictor activities on sheep rena l arteries, which can be inhibited by several antagonists, including a tropine, indomethacin, prazosin, and verapamil. 3. Mepyramine, yohimbi ne, and ketanserin have negligible effects on SES-induced contraction. 4. SES exhibits a significant tachyphylaxis upon addition of a second (8.4% reduction) and third (47% reduction) dose of SES to the organ b ath, which can be partially prevented by addition of a fresh arterial section prior to each addition. 5. A vasoconstricting activity has bee n partially purified from SES by gel filtration on Fractogel HW-65(F) and appears to be a protein with a pI near 7.3. This activity is affec ted only by verapamil and prazosin. (C) 1997 Elsevier Science Inc.