Inhibition by tosyl-L-phenylalanyl chloromethyl ketone of membrane potential changes in rat neutrophils. Correlation with the inhibition of biological activity.
A plasma membrane-associated serine esterase (protease) has previously been reported to be required during stimulation of a variety of cell types. In this study we have examined the role of such a protease on membrane potential changes using an optical probe of membrane potential 3,3'-dipropylthiodicarbocyanine iodide. The irreversible chymotrypsin-like protease inhibitor TPCK (tosyl-L-phenylalanyl chloromethyl ketone) inhibited membrane potential changes in rat neutrophils in response to phorbol myristate acetate, N-formylmethionylleucylphenylalanine and the calcium ionophore A23187 in a time- and dose-dependent manner. This inhibition was correlated with the known inhibitory effects on superoxide (O-2) generation and enzyme release (lysozyme and beta-glucuronidase). High external calcium concentrations overcame the inhibitory effects of TPCK on A23187-induced stimulation but had no effect on the inhibition of N-formylmethionylleucylphenylalanine stimulation. These results suggest that a TPCK-inhibitable activity is required for the development of the membrane potential changes that are coupled to subsequent secretory events and precede a calcium requiring activity.
D000085:Acetates / Q000494:pharmacology; D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology; D002634:Chemotaxis, Leukocyte; D066298:In Vitro Techniques; D007700:Kinetics; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D009113:Muramidase / Q000097:blood; D009504:Neutrophils / Q000502:physiology*; D051381:Rats; D013050:Spectrometry, Fluorescence; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014108:Tosylphenylalanyl Chloromethyl Ketone / Q000494:pharmacology*; D014634:Valinomycin / Q000494:pharmacology
D000085:Acetates; D000590:Amino Acid Chloromethyl Ketones; D014634:Valinomycin; D014108:Tosylphenylalanyl Chloromethyl Ketone; D009113:Muramidase; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium