Effects of adenosine deaminase on the sensitivity of glucose transport, glycolysis and glycogen synthesis to insulin in muscles of the rat

1. Soleus, extensor digitorum longus (EDL) or hemi-diaphragm muscles of the rat were incubated in the presence of insulin and rates of the processes of glycolysis and glycogen synthesis were measured. 2. The concentrations of insulin required to cause half-maximal stimulation of glycolysis in both soleus and EDL preparations were significantly decreased by the presence of adenosine deaminase in the medium. 3. Adenosine deaminase increased the sensitivity of the process of hexose transport to insulin (in an identical manner to the change in sensitivity of glycolysis) in the EDL preparation. 4. None of the adenosine mediated effects on insulin-stimulated rates of glycolysis were observed in the hemi-diaphragm preparation or on the rates of glycogen synthesis in any of the three muscle preparations. 5. Therefore, changes in the adenosine system in skeletal muscle influence insulin sensitivity regardless of fibre type composition of the muscle.     

Linkage analysis of the murine mos proto-oncogene on chromosome 4

A linkage analysis of the murine Mos gene, which codes for the c-mos proto-oncogene, was performed in 88 backcross progeny of an interspecies cross of laboratory mice and Mus spretus. Linkage was tested for four different genes on mouse chromosome 4: Aco-1, Mup-1, b, and Ifb. The gene order (from centromere) with intervening percentage recombination is Mos-15.9 (+/- 3.9)-Aco-1-5.6 (+/- 2.4)-Mup-1-3.4 (+/- 1.9)-b-5.6 (+/- 2.4)-Ifb. These results confirm the previous assignment of Mos to chromosome 4 on the basis of segregation in somatic cell hybrids (D. Swan et al., 1982, J. Virol. 44: 752-754) and show furthermore that Mos and the Ifa/Ifb clusters are not tightly linked as a group of intronless genes, but are separated by a map distance of 30.6 +/- 4.9 recombination units. The linkage data obtained in the present study place Mos in a region compatible with the physical map (D. W. Threadgill and J. E. Womack, 1988, Genomics 3: 82-86).     

The uptake of liposome-entraped 125I-labelled poly(vinylpyrrolidone) by rat jejunum in vitro

The uptake of free and liposome-entrapped ¹²⁵I-labelled poly(vinylpyrrolidone) was measured in an intestinal sac preparation from adult rats. An an equal concentration of ¹²⁵I-labelled poly(vinylpyrrolidone), the rate of uptake of the liposome-entrapped material was four times that of the free macromolecule.     

Effect of in vivo prostaglandin treatment on 3H-PGF2α uptake in hamster corpora lutea

Pregnant hamsters were administered (SC) prostaglandin or vehicle on the morning of the 4th day of pregnancy. Serum progesterone was significantly depressed (p<.01) at 0.5, 2, and 6 hours after treatment with 100 μg PGF_2α. Serum progesterone levels were unchanged 2 hours and 6 hours after treatment with 100 μg PGF_2β and 2 hours after treatment with 1 mg PGF_2β. Progesterone levels were depressed to less than 1 ng/ml 6 hours after treatment with 1 mg PGF_2β. The specific uptake of ³H-PGF_2α in whole hamster corpora lutea was significantly depressed 2 hours and 6 hours following 100 μg PGF_2α treatment. A 15% depression in specific uptake occurred 0.5 hour post-treatment. Treatment with 100 μg PGF_2β resulted in no change. Administration of 1 mg PGF_2β resulted in depressed ³H-PGF_2α uptake at both 2 and 6 hours post-treatment.Prostacyclin (PGI₂) treatment resulted in no change in either ³H-PGF_2α specific uptake or serum progesterone 2 hours after 100 μg treatment SC. These parameters were both reduced approximately 30% 6 hours post-treatment. Treatment with 6-keto-PGF_1α resulted in a complete lack of measurable ³H-PGF_2α uptake and serum progesterone levels less than 1 ng/ml at both 2 and 6 hours after treatment with 1 mg SC.