title: The action of peptides and proteases on the arachidonate cascade of human and rat platelets.
abstract: The arachidonate cascade of human or rat platelets were found to be modified by peptides (bradykinin, angiotensin I, angiotensin II, Asp1-Val5-angiotensin II-amide, somatostatin) and proteases (trypsin, kallikrein). The lipoxygenase pathway was not altered by angiotensin I, angiotensin II, trypsin and kallikrein, while the synthesis some of the cyclooxygenase products was selectively changed by these substances. Bradykinin and somatostatin resulted in an attenuated formation of 12-HPETE and 12-HETE - U shape dose response curve, at the same time the synthesis of cyclooxygenase metabolites was increased - bell shape dose response curve. Asp1-Val5-angiotensin II-amide increased the synthesis of lipoxygenase products and diminished the formation of TxB2. At the same time this peptide selectively induced the enzymatic release of PGD2 from platelets. These peptides and proteolytic enzymes might have physiologic significance in the "Ying-Yang" balance in one hand between lipoxygenase and cyclooxygenase metabolites and on the other between the proaggregatory and antiaggregatory substances released from platelets.
mesh_terms: D000809:Angiotensins / Q000494:pharmacology; D000818:Animals; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000097:blood*; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism*; D001920:Bradykinin / Q000494:pharmacology; D006801:Humans; D007610:Kallikreins / Q000502:physiology; D007700:Kinetics; D010447:Peptide Hydrolases / Q000494:pharmacology*; D010455:Peptides / Q000494:pharmacology*; D051381:Rats; D013004:Somatostatin / Q000494:pharmacology; D014357:Trypsin / Q000494:pharmacology
chemical_list: D000809:Angiotensins; D001095:Arachidonic Acids; D010455:Peptides; D016718:Arachidonic Acid; D013004:Somatostatin; D010447:Peptide Hydrolases; D007610:Kallikreins; D014357:Trypsin; D001920:Bradykinin