geoscience.net logo
+ Resolve Article
+ Follow Us
Follow on FacebookFollow on Facebook
Follow on TwitterFollow on Twitter

+ Translate
+ Subscribe to Site Feed
GeoScience Most Shared ContentMost Shared Content

Cylic AMP inhibition of mammary gland lactose synthesis: specificity and potentiation by 1-methyl-3-isobutylxanthine


, : Cylic AMP inhibition of mammary gland lactose synthesis: specificity and potentiation by 1-methyl-3-isobutylxanthine. Hormone and Metabolic Research 10(5): 415-419

When slices of lactating guinea pig mammary gland were incubated with 10-4 M 5'AMP, ATP, c[cyclic]AMP and cGMP, only the cAMP significantly inhibited lactose synthesis (26%). The drug 1-methyl-3-isobutylxanthine (MIX), a highly specific and potent inhibitor of cAMP phosphodiesterase, inhibited synthesis in a dose-response fashion from 10-5 to 10-3 M with 50% inhibition at approximately 10-4 M. Theophylline was approximately 1/3 more potent than MIX at 10-4 but equipotent at 10-3 M. Potentiation of dibutyryl cAMP (DBcAMP) by MIX, due to weak (24%) DBcAMP inhibition, was observed only with a low MIX concentration (10-5) combined with DBcAMP preincubation (0.degree. C, 30 min) resulting in a 33% inhibition by the 2 drugs together vs. 17% by MIX (P < 0.05). Inhibition was also observed with 8-p-chlorophenylthio-cAMP (CIPheS-cAMP), an analog reportedly 100.times. as potent as cAMP. C1PheS-cAMP produced the same 30-40% maximum inhibition as DBcAMP but with 1/100 the dose (10-7 M). Cholera toxin in the range 0.001-10 .mu.g/ml had no effect on release of lactose by gland slices over a 2 1/2-h period or on lactose synthesis. The experiments apparently demonstrate that cAMP inhibition of mammary gland lactose synthesis is weak but strongly specific and it is potentiated by phosphodiesterase inhibitors but the additivity is easily masked due to the potency of MIX. Lactating alveolar cells may be missing a receptor for cholera toxin or a transducer linking the receptor to adenylate cyclase.

US$19.90

PMID: 81796

DOI: 10.1055/s-0028-1093404


Other references

Moskvina, V.; Norton, N.; Williams, N.; Holmans, P.; Owen, M.; O'donovan, M., 2005: Streamlined analysis of pooled genotype data in SNP-based association studies. Several groups have developed methods for estimating allele frequencies in DNA pools as a fast and cheap way for detecting allelic association between genetic markers and disease. To obtain accurate estimates of allele frequencies, a correction fa...

Goette, D.K.; Odom, R.B., 1976: Atypical fibroxanthoma masquerading as pyogenic granuloma. An atypical fibroxanthoma on the ear of a 82-year-old man appeared clinically as a pyogenic granuloma. Histopathologically, the lesion had been interpreted as a malignant melanoma before its true nature was identified. Familiarity with this cutane...

Kimura, M.; Morise, K., 1990: Immunohistochemical studies of ulcerative colitis--expression of HLA-DR antigen by colonic epithelium and the role of dendritic cells in the lamina propria. In 27 patients with ulcerative colitis the colonic mucosa was analyzed by an immunohistochemical technique. A quantitative evaluation for lymphocyte subsets shows significantly-increased numbers of CD3+ cells, CD4+ cells, CD8+ cells and Leu7+ cell...

Kafetsios, K.; Hantzara, K.; Anagnostopoulos, F.; Niakas, D., 2015: Doctors' Attachment Orientations, Emotion Regulation Strategies, and Patient Satisfaction: A Multilevel Analysis. Extending recent research on emotion regulation in doctor-patient interaction, the present study examined relationships between doctors' attachment orientations, their emotion regulation strategies, and patients' satisfaction with the en...

Sener, E.; Davraz, A., 2013: Assessment of groundwater vulnerability based on a modified DRASTIC model, GIS and an analytic hierarchy process AHP method the case of Egirdir Lake basin Isparta, Turkey. A DRASTIC-model method based on a geographic information system (GIS) was used to study groundwater vulnerability in Egirdir Lake basin (Isparta, Turkey), an alluvial area that has suffered agricultural pollution. Lineament and land use were added...

Inskeep, W.P.; McDermott, T.R.; Fendorf, S., 2002: Arsenic (V)/(III) cycling in soils and natural waters: chemical and microbiological processes. This chapter focuses primarily on chemical and microbiological processes that mediate transformations between As(III) and As(V) to: (i) provide an updated review of the important chemical processes that control the distribution and speciation of A...

Naughton, J.M.; Smith, R., 1982: An electronmicroscopic study of the distribution of myelin basic protein in multilayer dispersions of diacylphosphatidylserine. Although dispersions containing lipid and protein are widely used as model systems to explore the properties of biomembranes, the extent of mixing of the two components has generally not been determined. Here, the distribution of bovine myelin bas...

Pospisilova D.; Svobodova V., 1992: Problems of giardiasis in persons keeping dogs and cats. In subjects with positive giardiasis tests examinations of contacts were made not only in all members of the family but also in dogs and cats living with them in the same household. Attention was paid to the possible transmission of giardias. A to...

Boys, C.; Cunningham, C.; McKenna, D.; Robertson, P.; Weeks, D.J.; Wishart, J., 2008: Prenatal screening for Down's syndrome: editorial responsibilities. Lancet 372(9652): 1789-1791

Stokke, T.; Kettler, D., 1985: Complications of continuous arteriovenous hemofiltration. Among annually 10 treatments with continuous arteriovenous haemofiltration (CAVH) during the last years there were some individual instances of severe complications: occluding thrombus in the femoral artery, infection at the site where the arteria...