Effect of forskolin on bradykinin-induced calcium mobilization in cultured canine tracheal smooth muscle cells.
The effects of increases in intracellular adenosine 3':5'-cyclic monophosphate (cyclic AMP) on bradykinin (BK)-induced generation of inositol phosphates (IPs) and Ca2+ mobilization were investigated in canine cultured tracheal smooth muscle cells (TSMCs). Pretreatment of TSMCs with either forskolin or dibutyryl cyclic AMP attenuated BK-stimulated responses. The inhibitory effects of these agents produced both a depression of the maximal response and a shift to the right of the concentration-response curves of BK. The water-soluble forskolin analogue L-858051, 7-deacetyl-7 beta-(r-N-methylpiperazino)-butyryl forskolin, significantly attenuated BK-stimulated IPs accumulation, while 1,9-dideoxy forskolin, an inactive forskolin, had little effect on IPs response. Moreover, SQ-22536, 9-(tetrahydro-2-furanyl)-9-H-purin-6-amine, an inhibitor of adenylate cyclase, and both H-89, N-(2-aminoethyl)-5-isoquinolinesulfonamide, and HA-1004, N-(2-guanidinoethyl)-5-isoquinolinesulfonamide, inhibitors of cyclic AMP-dependent protein kinase (PKA), reversed the ability of forskolin to attenuate BK-stimulated IPs accumulation. The KD and Bmax, values of the BK receptor for [3H]BK binding were not significantly changed by forskolin treatment for 30 min and 4 h. The AlF4(-)-induced IPs accumulation was attenuated by forskolin, indicating that G protein(s) are directly activated by AlF4- and uncoupled to phospholipase C by forskolin treatment. These results suggest that activation of cyclic AMP/PKA might inhibit the BK-stimulated PI breakdown and consequently reduce the [Ca2+]i increases or inhibit independently both responses, which is distal to the BK receptor in canine cultured TSMCs.
Luo
S F
SF
Department of Internal Medicine, Chang Gung College of Medicine and Technology, Kwei-San, Tao-Yuan, Taiwan.
Chiu
C T
CT
Tsao
H L
HL
Fan
L W
LW
Tsai
C T
CT
Pan
S L
SL
Yang
C M
CM
D000225:Adenine / Q000031:analogs & derivatives / Q000494:pharmacology; D000067956:Adenylyl Cyclase Inhibitors; D000262:Adenylyl Cyclases / Q000502:physiology; D017607:Aluminum Compounds / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D001920:Bradykinin / Q000378:metabolism / Q000494:pharmacology*; D003994:Bucladesine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002463:Cell Membrane Permeability / Q000187:drug effects; D002478:Cells, Cultured; D005576:Colforsin / Q000031:analogs & derivatives / Q000494:pharmacology*; D000242:Cyclic AMP / Q000502:physiology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000502:physiology; D004285:Dogs; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D005459:Fluorides / Q000494:pharmacology; D007295:Inositol Phosphates / Q000378:metabolism; D008297:Male; D009130:Muscle, Smooth / Q000378:metabolism*; D018002:Receptors, Bradykinin / Q000378:metabolism; D012503:Saponins / Q000494:pharmacology; D015398:Signal Transduction / Q000502:physiology; D014132:Trachea / Q000166:cytology / Q000378:metabolism*
D000067956:Adenylyl Cyclase Inhibitors; D017607:Aluminum Compounds; D004791:Enzyme Inhibitors; D007295:Inositol Phosphates; D018002:Receptors, Bradykinin; D012503:Saponins; C017759:9-(tetrahydro-2-furyl)-adenine; D005576:Colforsin; D003994:Bucladesine; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D000262:Adenylyl Cyclases; D000225:Adenine; D005459:Fluorides; D001920:Bradykinin; D002118:Calcium; C032311:aluminum fluoride