THE ANTAGONISTIC ACTION OF METHYLTHIOURACIL ON THE INHIBITORY EFFECT OF THYROXIN ON SERUM LIPASE

In rat pinealocytes, amiloride can modulate adrenergic-stimulated cyclic nucleotide accumulation. In this study, the effect of amiloride on melatonin production was characterized. Addition of 5-(N,N-hexamethylene)amiloride, a potent inhibitor of the Na(+)-H+ antiport, dose dependently inhibited norepinephrine- and isoproterenol-stimulated N-acetyltransferase (NAT) activity and melatonin production. Similar inhibition was also observed when pineal melatonin synthesis was stimulated directly with forskolin or dibutyryl adenosine 3',5'-cyclic monophosphate (cAMP), suggesting that the site of inhibition is distal to cAMP accumulation. Similarities between the inhibitory potencies of amiloride derivatives on the Na(+)-H+ antiport and pineal melatonin synthesis indicate that the observed inhibition on pineal melatonin synthesis by amilorides may be secondary to their actions on the Na(+)-H+ antiport. Further studies also indicate that the inhibitory effect of amilorides was not secondary to its cytotoxic actions and that amilorides had no direct antagonistic action on NAT activity. Our findings, therefore, suggest that, in addition to their effects on cyclic nucleotide accumulation, the Na(+)-H+ antiport also plays an important role in the cAMP-mediated melatonin synthesis in the rat pineal gland.

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Antagonistic Action of Lactobacillus acidophilus Toward Intestinal and Foodborne Pathogens in Associative Cultures1

Journal of Food Protection ◽

10.4315/0362-028x-40.12.820 ◽

1977 ◽

Vol 40 (12) ◽

pp. 820-823 ◽

Cited By ~ 171

Author(s):

S. E. GILLILAND ◽

M. L. SPECK

Keyword(s):

Escherichia Coli ◽

Hydrogen Peroxide ◽

Staphylococcus Aureus ◽

Foodborne Pathogens ◽

Lactobacillus Acidophilus ◽

Inhibitory Effect ◽

Enteropathogenic Escherichia Coli ◽

Anaerobic Conditions ◽

Antagonistic Action ◽

E Coli

Lactobacillus acidophilus exerted antagonistic actions on growth of Staphylococcus aureus, Salmonella typhimurium, enteropathogenic Escherichia coli, and Clostridium perfringens when grown with each in associative cultures. S. aureus and C. perfringens were more sensitive to the inhibition than were S. typhimurium and E. coli. The amount of the antagonism produced varied among strains of L. acidophilus and could not be directly related to amounts of acid produced; hydrogen peroxide produced by the lactobacilli appeared to be partially responsible for the antagonistic interaction. The inhibitory effect was produced also under anaerobic conditions in a pre-reduced medium.

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The antagonistic action of calcium upon the inhibitory effort of magnesium

Proceedings of the Royal Society of London. Series B, Containing Papers of a Biological Character ◽

10.1098/rspb.1908.0024 ◽

1908 ◽

Vol 80 (539) ◽

pp. 260-261 ◽

Cited By ~ 2

Keyword(s):

Inhibitory Effect ◽

Inhibitory Influence ◽

Intracerebral Injection ◽

Physiological Effects ◽

American Physiological Society ◽

Antagonistic Action ◽

Animal Body ◽

Magnesium Salts ◽

Calcium And Magnesium ◽

Prevailing View

Calcium and magnesium are chemically closely related elements. They are also close companions in the tissues of the animal body. It is the prevailing view that the physiological effects of both elements are similar in character. Many physiologists are at present of the opinion that calcium as well as magnesium exerts an inhibitory influence in the functions of the animal body. Loeb published, in 1899, his observations of the inhibitory action of calcium upon the twitchings of the frog muscles brought on by solutions of sodium chloride. It was then assumed by Loeb that all the members of the group of alkali earths possess inhibitory properties, including, at first, even barium. In the numerous subsequent papers by Lob and his pupils, the discussion turned, however, essentially around the inhibitory effect of calcium. As to magnesium, we have within the last few years published several studies in support of the hypothesis that magnesium salts favour inhibitory processes. The first fact which gave rise to that hypothesis was demonstrated in 1899 to the American Physiological Society. When an intracerebral injection of a few drops of a solution of magnesium sulphate caused a state of paralysis in a rabbit, while the injection of other solutions brought on convulsions.

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Chemical preservatives in foodstuffs. III Hexamethylenetetramine as mold inhibitor and the antagonistic action of amino acids

Agricultural and Food Science ◽

10.23986/afsci.71479 ◽

1959 ◽

Vol 31 (1) ◽

pp. 162-173

Author(s):

Reino R. Linko ◽

Olavi E. Nikkilä

Keyword(s):

Amino Acids ◽

Inhibitory Action ◽

Chemical Interaction ◽

Culture Media ◽

Inhibitory Effect ◽

Antagonistic Effect ◽

Antagonistic Action ◽

Rate Of Oxygen Consumption ◽

Chemical Preservatives ◽

Sulphydryl Compounds

Growth and respiration tests carried out on Aspergillus, Cladosporium and Penicillium molds have shown that certain amino acids such as 1-tryptophan and 1-cysteine and certain sulphydryl compounds such as glutathione and thioglycollic acid counteract the inhibitory action of hexamethylenetetramine. In the absence of hexamethylenetetramine, these compounds inhibit the growth of the molds. The dependence of the antagonistic action on the amino acid concentration differed for 1-cysteine and 1-tryptophan. The respiration of the mold was a maximum when equimolar concentrations of 1-cysteine and of the formaldehyde formed by the decomposition of hexamethylenetetramine were present in the culture media. The antagonistic effect of 1-tryptophan increased continuously with increasing concentration until the rate of oxygen consumption was the same as in the control test with no hexamethylenetetramine or antagonist present. The antagonistic effect of these four compounds on hexamethylenetetramine or on formaldehyde is evidently due to chemical interaction. The inhibitory effect of hexamethylenetetramine on the microbial cell may at least partly be due to its ability to inactivate enzymes such as the dehydrogenases.

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