Nonspecific effects of the pharmacological probes commonly used to analyze signal transduction in rabbit parietal cells.
In order to examine some possibly misleading conclusions of the pharmacological analysis of the signal transduction pathways of gastric acid secretion, we evaluated various agents including inhibitors of protein kinase C, cyclic AMP-dependent protein kinase, phospholipase C, phospholipase A2, lipoxygenase, casein kinase, calmodulin, myosin light chain kinase, tyrosine kinase, anion exchanger, and protein phosphatase; and activators of protein kinase C. Among them, the cyclic AMP-dependent protein kinase inhibitor N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinylsulfonamide (H-89), the phospholipase A2 inhibitor 2-(p-amylcinnamoyl)amino-4-chlorobenzoic acid (ONO-RS-082), three myosin light chain kinase inhibitors (1-(5-iodonaphthalene-1-sulfonyl)-1H-hexahydro-1,4-diazepine (ML-7), 1-(5-chloronaphthalene-1-sulfonyl)-1H-hexahydro-1,4-diazepine (ML-9), and wortmannin), the anion exchanger inhibitor 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS), the phospholipase C inhibitor neomycin, and most known calmodulin antagonists strongly inhibited [14C]aminopyrine accumulation, an indicator of acid secretion, in isolated rabbit gastric glands stimulated by N6,2'-O-dibutyryl-cyclic AMP. ONO-RS-082, calmidazolium, and DIDS inhibited H+,K+-ATPase. Most of the chemicals with antisecretory activity showed protonophore-like activity in gastric microsomes as well as in the mitochondria. It is concluded that H-89, ONO-RS-082, ML-7, ML-9, neomycin, and all calmodulin antagonists tested so far should not be used as tools to analyze gastric acid secretion.
Sugita
Y
Y
Laboratory of Pharmacology and Toxicology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo, Japan.
Nagao
T
T
Urushidani
T
T
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology; D062365:Aminobenzoates / Q000494:pharmacology; D000818:Animals; D034341:Aristolochic Acids; D016227:Benzoquinones / Q000494:pharmacology; D003994:Bucladesine / Q000494:pharmacology; D002147:Calmodulin / Q000037:antagonists & inhibitors; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002723:Chlorobenzoates; D002934:Cinnamates / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005744:Gastric Acid / Q000378:metabolism; D005753:Gastric Mucosa / Q000187:drug effects / Q000378:metabolism; D017506:H(+)-K(+)-Exchanging ATPase / Q000187:drug effects / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D009219:Myosin-Light-Chain Kinase / Q000037:antagonists & inhibitors; D009355:Neomycin / Q000494:pharmacology; D010295:Parietal Cells, Gastric / Q000187:drug effects / Q000502:physiology*; D010616:Phenanthrenes / Q000494:pharmacology; D010741:Phospholipases A / Q000037:antagonists & inhibitors; D054467:Phospholipases A2; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors; D047428:Protein Kinase Inhibitors; D011522:Protons; D011817:Rabbits; D015398:Signal Transduction; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors; D062367:ortho-Aminobenzoates