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(Hypertension. 2003;42:e1.)
© 2003 American Heart Association, Inc.

Letters to the Editor

B₂R of Bradykinin Activated by Proteases

Department of Pharmacology, University of Illinois College of Medicine, Chicago, Illinois

An extract of the first 250 words of the full text is provided, because this article has no abstract.

To the Editor:

We wish to correct the misstatements of our results¹ by Houle et al,² who quoted us: "The human B₂R has been proposed to be a specific binding site for serine proteases like human and porcine tissue kallikrein and trypsin, with pharmacological activation of these receptors on binding" (p. 611); "Tissue kallikrein exerts its effect on B₂R after high-affinity binding and without the need for a catalytically active enzyme" (p. 616). Both statements are attributed to our report, but they are the opposite of what we published¹ in abstract, on p. 831, para. 2, and on p. 834, para. 7; using cultured transfected or native cells, catalytically active enzyme is necessary to activate the bradykinin (BK) receptor and involving cleavage of a peptide bond. Just binding to B₂ R did not activate it¹ since inactive prokallikrein and DFP-treated kallikrein bind to B₂ R (Figure 7); conversely, trypsin or cathepsin G did not bind to (Figure 6, p. 832, para. 3, and p. 836, para. 3), but activated the native receptor (p. 830, paras. 6, 7, 11, and p. 831, para. 1).

These authors also exposed HEK 293 cells to undiluted human plasma. After rinsing cells they added rabbit kallikrein, released BK, and, in Western blot, showed kininogen (Figure 5). Elsewhere they found no competition binding with [³H]BK of kallikrein added to B₂-green fluorescent protein-expressing cells. They conclude that kallikrein’s effect on B₂ was due to kinin release, but elsewhere (p. 616) to limited proteolysis . . . [Full Text of this Article]

François Marceau; Steeve Houle

Centre Hospitalier Universitaire de Québec, Centre de recherche Pavillon l’Hôtel-Dieu de Québec, Québec, Canada

Giuseppe Molinaro; Albert Adam

Faculté de Pharmacie, Université de Montréal, Montréal, Canada