Impact of neonatal treatment with cardioactive glycosides (digoxin, ouabain) on receptor binding capacity, blood level and cardiac function in the adult rat. Extension of the imprinting theory

The ontogeny of asialoglycoprotein receptor was investigated by electron microscopic cytochemistry in hepatocytes isolated from foetal and adult rat. The binding capacity for asialofetuin coupled to horseradish peroxidase was lacking before the 18th day of intrauterine life; it arises at this time and increases with developmental age. The ligand-receptor complexes form small patches. The distribution pattern of positivity is very similar in pre and postnatal age, covering the entire cell surface. These results indicate a rather late appearance of the galactose-binding capacity related to the asialoglycoprotein clearance function, which is typical of adult mammalian liver.

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Androgen and glucocorticoid mechanisms in exercise-induced cardiac hypertrophy

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1984.246.6.h761 ◽

1984 ◽

Vol 246 (6) ◽

pp. H761-H767 ◽

Cited By ~ 1

Author(s):

R. C. Hickson ◽

T. M. Galassi ◽

T. T. Kurowski ◽

D. G. Daniels ◽

R. T. Chatterton

Keyword(s):

Cardiac Hypertrophy ◽

Receptor Binding ◽

Dissociation Constants ◽

Binding Capacity ◽

Rest Period ◽

Serum Testosterone ◽

Female Rats ◽

Total Serum ◽

Ventricular Tissue ◽

Exercise Induced

Female rats were trained daily by means of two 2-h-long bouts of swimming separated by a 30- to 40-min rest period. Absolute ventricular weights of the swimmers were increased above sedentary control values by 6% after 2 days, 15% after 7 days, and 30% after 35 days of exercise. Resting levels of total and free serum testosterone and total 5 alpha-dihydrotestosterone were not altered by the training. Total serum corticosterone concentrations at rest were significantly lower in the 7-day (149 +/- 16 ng/ml) and 35-day (169 +/- 24) swimmers compared with the controls (293 +/- 26). However, free corticosterone was not significantly reduced from controls in any of the swimming groups. Ventricular muscle cytosol androgen receptor binding dissociation constants and receptor binding capacities, measured using [3H]methyltrienolone (R1881), were not significantly different from control values in the exercised groups. Glucocorticoid cytosol receptor binding capacity in ventricular tissue, determined using [3H]dexamethasone, was significantly increased as femtomoles per milligram protein (39.3 +/- 3.1 vs. 31.4 +/- 1.4) and femtomoles per milligram DNA (2,683 +/- 226 vs. 1,786 +/- 71). These findings show that glucocorticoids, rather than androgens, undergo adaptive changes in the circulation and in muscle during the development of exercise-induced cardiac hypertrophy.

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Maturation of cholecystokinin receptors in pancreatic acini of rats

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1986.250.5.g594 ◽

1986 ◽

Vol 250 (5) ◽

pp. G594-G597 ◽

Cited By ~ 1

Author(s):

Y. K. Leung ◽

P. C. Lee ◽

E. Lebenthal

Keyword(s):

Receptor Binding ◽

Binding Capacity ◽

Amylase Secretion ◽

Newborn Rat ◽

Pancreatic Acini ◽

Binding System ◽

High Affinity ◽

Cholecystokinin Receptors ◽

Maximal Binding

Amylase secretion by fetal and newborn rat pancreata was shown not to respond to cholecystokinin (CCK) stimulation. Binding of 125I-Bolton-Hunter (125I-BH)-CCK-8 to dispersed pancreatic acini from rats at various perinatal ages was measured and compared with adults. Binding occurred maximally at 30 min at 37 degrees C at all ages. Maximal binding increased with age. The capacity and affinity of the CCK-receptor binding system was analyzed by Scatchard's method. The results revealed that the capacity of the high-affinity component gradually increases with age, whereas that of the low-affinity component remains relatively constant. Amylase secretion due to CCK stimulation also increases with age, suggesting that the lack of responsiveness of pancreata of pups to secretagogue is due to a low binding capacity of the high-affinity component of the receptors.

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The association in vitro of polyribosomes with ribonuclease-treated derivatives of hepatic rough endoplasmic reticulum. Characteristics of the membrane binding sites and factors influencing association

Biochemical Journal ◽

10.1042/bj1250067 ◽

1971 ◽

Vol 125 (1) ◽

pp. 67-79 ◽

Cited By ~ 47

Author(s):

T. K. Shires ◽

L. Narurkar ◽

H. C. Pitot

Keyword(s):

Rat Liver ◽

Binding Sites ◽

Binding Capacity ◽

Trypsin Treatment ◽

Partial Removal ◽

Adult Rat ◽

Microsomal Membranes ◽

Derivatives Of ◽

Membrane Binding Sites

1. Pancreatic ribonuclease in dilute EDTA has been shown to condition rough-microsomal membranes from adult rat liver to accept exogenously added rat liver polyribosomes in vitro at 0–4°C. Treated smooth membranes would not significantly interact with polyribosomes. 2. The conditioning process decreased the membrane RNA content and removed polyribosomes from vesicle surfaces as viewed electron-microscopically. 3. Binding to these conditioned membranes was shown to be uninfluenced by changes of temperature (0–37°C) and pH (6.9–7.8) or the presence of cell sap, but was inhibited by increasing the concentration of potassium chloride. 4. Possession of a polyribosome-binding capacity by conditioned rough membranes was not dependent on adventitious materials that could be dislodged by high ionic strengths. 5. Trypsin treatment under mild conditions destroyed the binding capacity of ribonuclease-conditioned rough membranes. 6. A 2–10S residual RNA was recovered from ribonuclease-conditioned membranes, but its partial removal had no effect on the capacity of membranes to accept polyribosomes. However, some role for this residual RNA in attaching polyribosomes could not be discounted. 7. Evidence is considered that polyribosome-binding sites are intrinsic features of conditioned membranes isolated from rough-microsomal fractions, and that long-range ionic bonding is a primary factor in polyribosome interaction with these binding sites.

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