scholarly journals Homologous β-adrenergic desensitization in isolated rat hepatocytes

1987 ◽  
Vol 246 (2) ◽  
pp. 331-336 ◽  
Author(s):  
J A García-Sáinz ◽  
B Michel
Keyword(s):  
Rat Hepatocytes ◽  
Time Dependent ◽  
Adrenergic Agonists ◽  
Isolated Rat Hepatocytes ◽  
Beta Adrenergic ◽  
Beta Adrenergic Agonists ◽  
Cyclic Amp Accumulation ◽  
Homologous Desensitization ◽  
Isolated Rat ◽  
Stimulation Of

Hepatocytes from hypothyroid rats have a marked beta-adrenergic responsiveness. Preincubation of these hepatocytes with isoprenaline induced a time-dependent and concentration-dependent desensitization of the beta-adrenergic responsiveness without altering that to glucagon (homologous desensitization). The desensitization was evidenced both in the cyclic AMP accumulation and in the stimulation of ureagenesis induced by the beta-adrenergic agonists. Under the same conditions, preincubation with glucagon induced no desensitization. Propranolol was also unable to induce desensitization, but blocked that induced by isoprenaline. Pertussis-toxin treatment did not alter the homologous beta-adrenergic desensitization induced by isoprenaline.

scholarly journals The mechanism by which adenosine decreases gluconeogenesis from lactate in isolated rat hepatocytes

1987 ◽  
Vol 246 (2) ◽  
pp. 449-454 ◽  
Author(s):  
A Lavoinne ◽  
H A Buc ◽  
S Claeyssens ◽  
M Pinosa ◽  
F Matray
Keyword(s):  
Ketone Body ◽  
Adenine Nucleotides ◽  
Rat Hepatocytes ◽  
Adenosine Kinase ◽  
Isolated Rat Hepatocytes ◽  
Adenosine Deaminase 2 ◽  
Body Production ◽  
Gluconeogenic Substrates ◽  
Isolated Rat ◽  
Stimulation Of

Incubation of hepatocytes from 24 h-starved rats in the presence of 0.5 mM-adenosine decreased gluconeogenesis from lactate, but not from alanine. The inhibition of gluconeogenesis was associated with a stimulation of ketone-body production and an inhibition of pyruvate oxidation. These metabolic changes were suppressed in the presence of iodotubercidin (an inhibitor of adenosine kinase), but were reinforced in the presence of deoxycoformycin (an inhibitor of adenosine deaminase); 2-chloroadenosine induced no change in gluconeogenesis from lactate. These data indicate that the inhibition of gluconeogenesis by adenosine probably results from its conversion into adenine nucleotides. In the presence of lactate or pyruvate, but not with alanine or asparagine, this conversion resulted in a decrease in the [ATP]/[ADP] ratio in both mitochondrial and cytosolic compartments. Adenosine decreased the Pi concentration with all gluconeogenic substrates.

Vasomotion in chicken foot: dual innervation of arteriovenous anastomoses

1982 ◽  
Vol 242 (5) ◽  
pp. R582-R590 ◽  
Author(s):  
P. E. Hillman ◽  
N. R. Scott ◽  
A. van Tienhoven
Keyword(s):  
Capillary Flow ◽  
Arteriovenous Anastomoses ◽  
Adrenergic Agonists ◽  
Beta Adrenergic ◽  
Beta Adrenergic Agonists ◽  
Collateral Vein ◽  
Flow Through ◽  
Purinergic Nerves ◽  
Counter Current ◽  
Stimulation Of

Blood exits the foot of the domestic chicken via two major venous routes: a counter-current network surrounding the major incoming artery and a large collateral vein. Between these two routes are numerous large collateral vein. Between these two routes are numerous anastomotic veins. Both venous routes drain capillaries and arteriovenous anastomoses (AVAs). Blood flow through the foot was measured on unanesthetized hens. Flow varies with ambient temperature: 0.2 ml/min at 5 degrees C, 2.2 ml/min at thermoneutrality, and 5.4 ml/min at 36 degrees C; the AVAs contribute 8, 26, and 63% to this flow, respectively. Flow through capillaries is reduced by alpha-adrenergic agonists and is increased by beta-adrenergic agonists. Blocking nerve conduction to the foot at thermoneutrality releases alpha-adrenergic tone and increase AVA flow. Faradic stimulation of foot nerves after adrenergic blockage increases AVA flow, but not capillary flow, suggesting active vasodilation of the AVAs. Such AVA vasodilation normally occurs during body heating, since AVA flow decreases after denervation. Dopaminergic or beta-adrenergic nerves are not involved in active vasodilatation, however, purinergic nerves may play a role. Thus AVAs have a functional dual innervation.

scholarly journals Effect of adenosine and inosine on ureagenesis in hepatocytes

1987 ◽  
Vol 245 (2) ◽  
pp. 371-374 ◽  
Author(s):  
R Guinzberg P ◽  
I Laguna ◽  
A Zentella ◽  
R Guzman ◽  
E Piña
Keyword(s):  
Uric Acid ◽  
Rat Hepatocytes ◽  
Physiological Significance ◽  
Isolated Rat Hepatocytes ◽  
Dose Dependent ◽  
Isolated Rat ◽  
Stimulation Of

Adenosine and inosine produced a dose-dependent stimulation of ureagenesis in isolated rat hepatocytes. Hypoxanthine, xanthine and uric acid were without effect. Half-maximally effective concentrations were 0.08 microM for adenosine and 5 microM for inosine. Activation of ureagenesis by both nucleosides had the following characteristics: (a) it was observed with either glutamine or (NH4)2CO3, provided that glucose was present; (b) it was not detected when glucose was replaced by lactate plus oleate; (c) it was mutually antagonized by glucagon, but not by adrenaline; and (d) it was dependent on Ca2+. We suggest that the action of adenosine and inosine on ureagenesis might be of physiological significance.

scholarly journals Effects of adrenergic agonists on ketogenesis in isolated rat hepatocytes

1989 ◽  
Vol 49 ◽  
pp. 140
Author(s):  
Takahide Nomura ◽  
Masaru Chihara ◽  
Yukihiko Nomura ◽  
Masakatsu Tachibana ◽  
Hiroko Nomura ◽  
...  
Keyword(s):  
Rat Hepatocytes ◽  
Adrenergic Agonists ◽  
Isolated Rat Hepatocytes ◽  
Isolated Rat

scholarly journals The Effect of Thyroid Hormones on the Beta-Adrenergic Receptor Internalization in Isolated Rat Hepatocytes

1983 ◽  
Vol 59 (11) ◽  
pp. 1693-1702
Author(s):  
Kiyoshi HASHIZUME ◽  
Keishi YAMAUCHI ◽  
Mutsuhiro KOBAYASHI ◽  
Kazutaka HARAGUCHI ◽  
Kazuo ICHIKAWA
Keyword(s):  
Thyroid Hormones ◽  
Adrenergic Receptor ◽  
Rat Hepatocytes ◽  
Receptor Internalization ◽  
Beta Adrenergic Receptor ◽  
Isolated Rat Hepatocytes ◽  
Beta Adrenergic ◽  
Isolated Rat

α1B-Adrenoceptor-mediated stimulation of Ca2+ mobilization and cAMP accumulation in isolated rat hepatocytes

1993 ◽  
Vol 246 (2) ◽  
pp. 113-120 ◽  
Author(s):  
Takahide Nomura ◽  
Haruhito Kondo ◽  
Seiko Hasegawa ◽  
Toshiko Watanabe ◽  
Rie Yokoyama ◽  
...  
Keyword(s):  
Rat Hepatocytes ◽  
Camp Accumulation ◽  
Isolated Rat Hepatocytes ◽  
Isolated Rat ◽  
Stimulation Of
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