Vasodilation responses to matricryptic plasma fibronectin peptides (FNp) depend on beta adrenergic receptor pathways

Thermal burn progression is attenuated by post‐burn intravenous injection of a synthetic FNp modeled after a matricryptic site within plasma FN. We hypothesized that one mechanism was via improvement in microvascular flow within the vicinity of the thermal burn, by inducing dilation. The cheek pouch of anesthetized (pentobarbital 70 mg/kg) hamsters (N=69) was prepared for observation of terminal arteriolar networks. Full length FN, 5 unique FNp, and 2 scrambled FNp were tested by micropipette application of the test agents [10‐15‐10‐4M] directly to the abluminal surface of the terminal arterioles. Uniformly, lower concentrations of FNp induced a robust dilation, while 10‐6M and above induced a robust constriction. The scrambled FNp induced only constriction. Adrenergic blockade with propranolol and phentolamine blocked only the dilatory component and was without effect on constriction. The most to least potent (dilation occurring at the lowest doses): RWRPK > LRWRPK > ILRWRPK = YILRWRPK > PSHISKYILRWRPK. The most to least efficacious (largest maximal dilation): ILRWRPK = YILRWRPK > PSHISKYILRWRPK > RWRPK >> LRWRPK. In comparison, full length FN induced only dilation that was as potent and efficacious as ILRWRPK, but was only tested to 10‐6M. Thus, FNp that are predicted to be released from plasma FN with tissue injury induce a robust dilation at pM to nM concentrations. Thanks to AHA 0655908T and AFIRM.