Biomaterial Database

Pitfalls in the use of lead nitrate for the histochemical demonstration of adenylate cyclase activity. 1975

A Lemay, and L Jarett

The biochemistry of the lead histochemical technique for demonstrating adenylate cyclase was studied. The enzyme activity of fat cell plasma membranes, using 5'-adenylyl-imidodiphosphate (AMP-PNP) as substrate, was completely inhibited at 1 times 10- minus 4 M Pb(NO3)2 and yet at 4 times 10- minus 3 M Pb(NO3)2 precipitate could be demonstrated by electron microscopy on both sides of plasma membrane vesicles. No lead-diphosphoimide or lead-phosphate precipitate could be visualized by electron microscopy when the lead was reduced to a level (2 times 10- minus 5 M) which caused only 50% inhibition of the enzyme. A solubility product coefficient of 1 times 10- minus 10 M was found necessary to allow precipitation of lead-phosphate complex in the adenylate cyclase medium. Varying the ratio of substrate or dextran relative to the lead failed to protect the inhibition of the enzyme. Increasing concentrations of beta-mercaptoethanol restored the basal and stimulated activity of adenylate cyclase but also prevented the precipitation reaction. Lead at 2 times 10- minus 3 M caused the nonenzymatic hydrolysis of AMP-PNP, resulting in the production of small but significant quantities of cyclic AMP and substantial amounts of AMP. This hydrolysis was inhibited by alloxan but unaffected by dextran of NaF. The adenylate cyclase activity of pancreatic islet homogenates and of fat pad capillaries was completely inhibited by lead concentrations equal to or less than those used in histochemical studies (Howell, S. L., and M. Whitfield. 1972. J. Histochem. Cytochem. 20:873-879. and Wagner, R. C., P. Kreiner, R. J. Barrnett, and M. W. Bitensky. 1972. Proc. Natl. Acad. Sci. U.S.A. 69:3175-3179.). The present study shows that the lead histochemical method cannot be used for localization of adenylate cyclase because of the inhibition of the enzyme and artifacts produced by high lead concentrations and the inability to produce a visible precipitate at low lead concentrations which only partially inhibit the enzyme.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D007854	Lead	A soft, grayish metal with poisonous salts; atomic number 82, atomic weight 207.2, symbol Pb.
D008722	Methods	A series of steps taken in order to conduct research.	Techniques,Methodological Studies,Methodological Study,Procedures,Studies, Methodological,Study, Methodological,Method,Procedure,Technique
D008854	Microscopy, Electron	Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.	Electron Microscopy
D009566	Nitrates	Inorganic or organic salts and esters of nitric acid. These compounds contain the NO3- radical.	Nitrate
D010727	Phosphoric Diester Hydrolases	A class of enzymes that catalyze the hydrolysis of one of the two ester bonds in a phosphodiester compound. EC 3.1.4.	Phosphodiesterase,Phosphodiesterases,Hydrolases, Phosphoric Diester
D002462	Cell Membrane	The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.	Plasma Membrane,Cytoplasmic Membrane,Cell Membranes,Cytoplasmic Membranes,Membrane, Cell,Membrane, Cytoplasmic,Membrane, Plasma,Membranes, Cell,Membranes, Cytoplasmic,Membranes, Plasma,Plasma Membranes
D004837	Epinephrine	The active sympathomimetic hormone from the ADRENAL MEDULLA. It stimulates both the alpha- and beta- adrenergic systems, causes systemic VASOCONSTRICTION and gastrointestinal relaxation, stimulates the HEART, and dilates BRONCHI and cerebral vessels. It is used in ASTHMA and CARDIAC FAILURE and to delay absorption of local ANESTHETICS.	Adrenaline,4-(1-Hydroxy-2-(methylamino)ethyl)-1,2-benzenediol,Adrenaline Acid Tartrate,Adrenaline Bitartrate,Adrenaline Hydrochloride,Epifrin,Epinephrine Acetate,Epinephrine Bitartrate,Epinephrine Hydrochloride,Epinephrine Hydrogen Tartrate,Epitrate,Lyophrin,Medihaler-Epi,Acetate, Epinephrine
D005069	Evaluation Studies as Topic	Works about studies that determine the effectiveness or value of processes, personnel, and equipment, or the material on conducting such studies.	Critique,Evaluation Indexes,Evaluation Methodology,Evaluation Report,Evaluation Research,Methodology, Evaluation,Pre-Post Tests,Qualitative Evaluation,Quantitative Evaluation,Theoretical Effectiveness,Use-Effectiveness,Critiques,Effectiveness, Theoretical,Evaluation Methodologies,Evaluation Reports,Evaluation, Qualitative,Evaluation, Quantitative,Evaluations, Qualitative,Evaluations, Quantitative,Indexes, Evaluation,Methodologies, Evaluation,Pre Post Tests,Pre-Post Test,Qualitative Evaluations,Quantitative Evaluations,Report, Evaluation,Reports, Evaluation,Research, Evaluation,Test, Pre-Post,Tests, Pre-Post,Use Effectiveness
D005459	Fluorides	Inorganic salts of hydrofluoric acid, HF, in which the fluorine atom is in the -1 oxidation state. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed) Sodium and stannous salts are commonly used in dentifrices.	Fluoride