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C R Bacon

Publications and source records attributed to C R Bacon.

6 recordsLinked to original sources
PubMed1993

Human endothelin receptors characterized using reverse transcriptase-polymerase chain reaction, in situ hybridization, and subtype-selective ligands BQ123 and BQ3020: evidence for expression of ETB receptors in human vascular smooth muscle.

Our aim was to characterize and determine the function of endothelin (ET) receptor subtypes in human vascular tissue. Reverse transcriptase-polymerase chain reaction with nested oligonucleotide primers detected the presence of mRNA encoding both ETA and ETB receptors in the media from aorta and pulmonary and coronary arteries. In situ hybridization confirmed the presence of mRNA for both subtypes in the media of coronary arteries. Saturation binding assays using 125I-ET-1 found a single population of high-affinity ET receptors (n = three patients, +/- SEM) in aorta (Kd = 0.507 +/- 0.020 nM; Bmax = 9 +/- 4 fmol/mg protein) and pulmonary (Kd = 0.845 +/- 0.245 nM; Bmax = 15 +/- 10 fmol/mg protein) and coronary arteries (Kd = 0.141 +/- 0.020 nM; Bmax = 71 +/- 21 fmol/mg protein). Using media from coronary arteries, the ETA-selective ligand BQ123 (cyclo[D-Asp-L-Pro-D-Val-L-Leu-D-Trp]) and the ETB-selective ligand BQ3020 (Ala11,15-Ac-ET-1[6-21]) both produced biphasic competition binding curves against 125I-ET-1, confirming the presence of high- and low-affinity sites corresponding to the two subtypes: BQ123 (KdETA = 0.85 +/- 0.03 nM; KdETB = 7.58 +/- 2.27 microM; ETA/ETB, 87%:13%) and BQ3020 (KdETA = 0.22 +/- 0.04 microM; KdETB = 0.77 +/- 0.34 nM; ETA/ETB, 62%:38%). BQ123 (0.1 microM) caused a significant parallel rightward shift of ET-1-induced vasoconstriction of coronary arteries in vitro, but BQ3020 and Ala1,3,11,15-ET-1 failed to show any agonist activity when tested at concentrations of < or = 3 microM in three vessels.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Protein metabolism during nutrient deprivation and refeeding of neonatal heart cells.

Pathological conditions or nutrient deprivation in the heart cause an imbalance between rates of protein synthesis and degradation, often resulting in a severe depletion of cardiac protein. We used cultured neonatal rat heart cells, a model system exhibiting positive nitrogen balance, to examine the effects of 10 h of starvation on myocardial glucose and protein metabolism. Cellular capacity for glucose utilization was depressed after starvation, as evidenced by lower hexokinase and other glycolytic enzyme activities and a 21% decrease in glucose usage. A 21.0% decrease in protein synthetic rate and an increase in protein degradation rate combined to yield a 29.5% decrease in total cellular protein during starvation. Degradation rates increased 29.0, 46.7, and 59.6% in 2-, 24-, and 96-h prelabeled cells, respectively, indicating that lability increased with half-life of proteins. During refeeding of starved, cultured cells, at least three proteins were synthesized at a lower rate. At the same time, proteins with approximate molecular masses of 45, 84, 92, and 174 kDa exhibited increased synthesis.

Animals↗
PubMed1988

Hemin increases aerobic capacity of cultured regenerating skeletal myotubes.

Regeneration of damaged, mature muscle occurs by differentiation of satellite cells. In culture, satellite cell myoblasts proliferate, align, and fuse to form cross-striated, contracting myotubes. The biochemical changes and the factors that regulate differentiation in satellite cells have not been investigated previously. We report here that no significant differences in glucose uptake rate or glucose oxidation rate were observed between regenerating myoblasts and myotubes, whereas the aerobic oxidation of palmitic acid increased 7.3-fold between these differentiation states. Specific activities of enzymes of critical importance in aerobic metabolism or in production of ATP were increased 2- to 3.5-fold during fusion. Addition of 20 microM hemin to regenerating muscle cultures potentiated the aerobic capacity as evidenced by a 23.6% increase in palmitate oxidation rate. Hemin also increased the specific activities of all nonheme enzymes investigated with the exception of phosphofructokinase. This augmentation of aerobic metabolism together with the time frame of active muscle differentiation suggests a complex role for hemin in myogenesis.

Aerobiosis↗