Bradykinin B2 receptor-mediated phosphoinositide hydrolysis in bovine cultured tracheal smooth muscle cells.
1. Bovine tracheal smooth muscle cells were established in culture to study agonist-induced phosphoinositide (PI) hydrolysis in this tissue. 2. Bradykinin (0.1 nM-10 microM) evoked a concentration-dependent increase (log EC50 (M) = -9.4 +/- 0.2; n = 8) in the accumulation of total [3H]-inositol phosphates in cultured tracheal smooth muscle cells whereas the selective B1 receptor agonist des-Arg9-bradykinin (10 microM) was significantly less effective (16% of bradykinin maximal response; relative potency = 0.2 with respect to bradykinin = 100). 3. The bradykinin-induced increase in PI hydrolysis was unaffected by the B1 receptor antagonist des-Arg9[Leu8]-bradykinin (1 nM-1 microM) but showed marked attenuation in the presence of the B2 receptor antagonists D-Arg,[Hyp3,D-Phe7]-bradykinin (10 nM-10 microM) or D-Arg[Hyp3,Thi5,8,D-Phe7]-bradykinin (10 nM-10 microM). The estimated KB values obtained for these two compounds, assuming competitive antagonism, were 40 +/- 14 nM and 8.6 +/- 2.8 nM for D-Arg,[Hyp3,D-Phe7]-bradykinin and D-Arg[Hyp3,Thi5,8,D-Phe7]-bradykinin respectively. 4. We conclude that bradykinin B2 receptors are expressed in cultured bovine tracheal smooth muscle cells and are coupled to PI hydrolysis mechanisms.
Marsh
K A
KA
Department of Physiology and Pharmacology, Medical School, Queen's Medical Centre, Nottingham.
Hill
S J
SJ
D000818:Animals; D001920:Bradykinin / Q000031:analogs & derivatives / Q000494:pharmacology*; D002417:Cattle; D002478:Cells, Cultured; D006868:Hydrolysis; D009130:Muscle, Smooth / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D010716:Phosphatidylinositols / Q000378:metabolism*; D018002:Receptors, Bradykinin; D017981:Receptors, Neurotransmitter / Q000037:antagonists & inhibitors / Q000187:drug effects / Q000378:metabolism*; D014132:Trachea / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*
D010716:Phosphatidylinositols; D018002:Receptors, Bradykinin; D017981:Receptors, Neurotransmitter; D001920:Bradykinin