scholarly journals Hormonal control of gluconeogenesis in tubule fragments from renal cortex of fed rats. Effects of α-adrenergic stimuli, glucagon, theophylline and papaverine

1977 ◽  
Vol 168 (1) ◽  
pp. 33-42 ◽  
Author(s):  
David W. R. MacDonald ◽  
E. David Saggerson
Keyword(s):  
Parathyroid Hormone ◽  
Cyclic Amp ◽  
Cyclic Gmp ◽  
Cyclic Nucleotide ◽  
Renal Cortex ◽  
Glucose Production ◽  
Hormonal Control ◽  
Adrenergic Agonists ◽  
Renal Gluconeogenesis ◽  
Stimulation Of

1. In incubated tubule fragments from renal cortex of fed rats gluconeogenesis from pyruvate was stimulated by adrenaline (1μm optimum) and by the selective α-adrenergic agonists oxymetazoline and amidephrine. The selective β-agonists isoproterenol and salbutamol were ineffective at concentrations up to 10μm. 2. Stimulation of gluconeogenesis by 1μm-adrenaline was almost completely blocked by 10μm-phentolamine (α-antagonist), partially blocked by 10μm-phenoxybenzamine (α-antagonist) and unaffected by 10μm-propranolol (β-antagonist). 3. Adrenaline stimulation of gluconeogenesis was rapid and was sustained for at least 1h. 4. Oxymetazoline (α-agonist) was extremely potent in stimulation of gluconeogenesis. This compound stimulated glucose production from pyruvate, lactate and glutamate, but not from succinate or glycerol. 5. In the absence of Ca2+ oxymetazoline was ineffective, whereas some stimulatory effect of adrenaline on gluconeogenesis was still observed. 6. Glucagon had no effect on gluconeogenesis from pyruvate in the presence of 1.27mm-Ca2+ and inhibited the process in the presence of 0.25mm-Ca2+. Parathyrin (parathyroid hormone) stimulated gluconeogenesis at 1.27mm-Ca2+. 7. In short incubations of tubule fragments glucagon, papaverine and adrenaline significantly increased 3′:5′-cyclic AMP. Adrenaline also slightly decreased 3′:5′-cyclic GMP. Oxymetazoline had no effect on the amount of either cyclic nucleotide. 8. At all concentrations tested, theophylline and papaverine decreased gluconeogenesis from pyruvate. 9. It is concluded that renal gluconeogenesis may be increased by α- but not β-adrenergic stimuli and that this is probably independent of changes in 3′:5′-cyclic AMP or 3′:5′-cyclic GMP. An involvement of Ca2+ in the action of oxymetazoline appears likely, but this is less certain with adrenaline.

Cyclic nucleotides, calcium, bicarbonate, and protein secretion in canine pancreatic juice in response to cholecystokinin–pancreozymin

1979 ◽  
Vol 57 (6) ◽  
pp. 541-546 ◽  
Author(s):  
H. L. Cailla ◽  
H. Sarles ◽  
M. V. Singer
Keyword(s):  
Cyclic Amp ◽  
Pancreatic Juice ◽  
Cyclic Gmp ◽  
Cyclic Nucleotides ◽  
Parallel Increase ◽  
Calcium Bicarbonate ◽  
Strong Linear Correlation ◽  
Protein Output ◽  
Dose Dependent ◽  
Stimulation Of

The secretion of cyclic AMP, cyclic GMP, protein, calcium, and bicarbonate in the pancreatic juice of three nonanesthetized dogs with chronic gastric and duodenal Thomas cannulae has been studied. Intravenous infusions of increasing doses of cholecystokinin–pancreozymin (CCK) (1.5, 3, 6, 12, 24 Crick Harper-Raper (CHR) U kg−1 h−1) were administered together with a continuous submaximal dose of secretin (1 clinical unit (CU) kg−1 h−1). Doubling CCK doses every 45 min induced a parallel increase in the output of both cyclic nucleotides. Cyclic AMP output peaked at between 15 and 30 min for 3 and 6 U kg−1 h−1 of CCK and later for 12 and 24 U kg−1 h−1 of CCK whereas cyclic GMP output increased more constantly. Calcium output followed a pattern similar to that of cyclic GMP secretion. Flow rate and protein output attained their peaks at between 30 and 45 min. A strong linear correlation was found between the quantities of cyclic AMP, cyclic GMP, and the quantities of protein secreted in response to each CCK dose. This study demonstrates the presence of cyclic GMP in the canine pancreatic juice and the dose-dependent stimulation of the secretion of cyclic GMP and cyclic AMP by CCK in the presence of secretin.

Possible role of cyclic GMP in stimulus-secretion coupling by salt gland of the duck

1979 ◽  
Vol 237 (5) ◽  
pp. C200-C204 ◽  
Author(s):  
D. J. Stewart ◽  
J. Sax ◽  
R. Funk ◽  
A. K. Sen
Keyword(s):  
Cyclic Amp ◽  
Guanylate Cyclase ◽  
Cyclic Gmp ◽  
Salt Gland ◽  
Domestic Ducks ◽  
Stimulus Secretion Coupling ◽  
Stimulation Of

Stimulation of salt galnd secretion in domestic ducks in vivo increased the cyclic GMP concentration of the tissue, but had no effect on cyclic AMP levels. Methacholine, which is known to stimulate sodium transport by the glands both in vivo and in vitro, stimulated ouabain-sensitive respiration in salt gland slices. Cyclic GMP stimulated ouabain-sensitive respiration to the same extent as methacholine. Guanylate cyclase stimulators, hydroxylamine and sodium azide, also stimulated ouabain-sensitive respiration. The stimulation of ouabain-sensitive respiration by methacholine was blocked either by atropine or by removal of calcium from the incubation medium. The stimulation of ouabain-sensitive respiration by cyclic GMP still occurred in the absence of calcium. The above observations seem to indicate that cyclic GMP acts as a tertiary link in the process of stimulus-secretion coupling in the tissue.

Lithium administration and phosphate excretion

1976 ◽  
Vol 231 (4) ◽  
pp. 1140-1146 ◽  
Author(s):  
JA Arruda ◽  
JM Richardson ◽  
JA Wolfson ◽  
L Nascimento ◽  
DR Rademacher ◽  
...  
Keyword(s):  
Parathyroid Hormone ◽  
Cyclic Amp ◽  
Renal Cortex ◽  
Cyclic Adenosine Monophosphate ◽  
Fractional Excretion ◽  
Adenosine Monophosphate ◽  
Adenyl Cyclase ◽  
Phosphate Excretion ◽  
Camp System

The phosphaturic effect of parathyroid hormone (PTH), cyclic adenosine monophosphate (cAMP), acetazolamide (Az), and HCO3 loading was studied in normal, thyroparathyroidectomized (TPTX), and Li-treated dogs. PTH administration to normal animals markedly increased fractional excretion (F) of PO4 but had a blunted effect on FPO4 in the Li-treated animals. Cyclic AMP likewise markedly increased FPO4 in the normal animals but had a markedly blunted effect in the Li-treated animals. Az led to a significant increase in FNa, FHCO3, and FPO4 in the normal animals. In the Li-treated dogs, Az induced a significant natriuresis and bicarbonaturia but failed to increase phosphaturia. HCO3 loading in normal dogs caused a significant phosphaturia while having little effect on FPO4 in Li-treated dogs. HCO3 loading to TPTX dogs was associated with a lower FPO4 as compared to normal HCO3-loaded animals. These data suggest that Li administration not only blocks the adenyl cyclase-cAMP system in the renal cortex, but it may also interfere with a step distal to the formation of cAMP, since the phosphaturic effect of both PTH and cAMP was markedly diminished in Li-treated animals.

Renal gluconeogenesis: axial and internephron heterogeneity and the effect of parathyroid hormone

1984 ◽  
Vol 246 (1) ◽  
pp. F59-F66 ◽  
Author(s):  
M. S. Wang ◽  
K. Kurokawa
Keyword(s):  
Parathyroid Hormone ◽  
Calcium Ions ◽  
Glucose Production ◽  
Cellular Responses ◽  
Nephron Segments ◽  
Renal Gluconeogenesis ◽  
The Difference ◽  
Proximal Tubule Segments ◽  
Camp Formation ◽  
Gluconeogenic Substrate

To better understand the regulation of renal gluconeogenesis that occurs in the proximal nephron, glucose production rates from various substrates were determined in defined proximal tubule segments of the rat. Tubule segments tested were the S1 and S2 segments of superficial (SF) nephrons, the S1 segments of juxtamedullary (JM) nephrons, and the S3 segments. Glucose production (in decreasing order) was: from alpha-ketoglutarate, JM S1, SF S1, SF S2; from pyruvate, SF S2, JM S1, and SF S1; from glutamine, SF S1, JM S1; and from glutamate, SF S1 = JM S1. Little glucose was produced in the S3 segments. Glucose production from glutamate was lower than that from the other three substrates in JM S1, and glutamine was the best gluconeogenic substrate in SF S1. The effects of parathyroid hormone (PTH), a known stimulator of renal gluconeogenesis, and cAMP were examined using alpha-ketoglutarate as the substrate. Both stimulated glucose production in the S1 and S2 segments of the SF nephron. Although PTH stimulated adenylate cyclase in the S1 segments of the SF and JM nephrons, it had no effect on glucose production in the JM S1. Glucose production rose in the SF S1 and JM S1 in response to increasing concentrations of hydrogen or calcium ions, indicating that gluconeogenesis can be increased in these nephron segments. Differences may therefore be present in the cellular responses to PTH distal to cAMP formation in the nephron segments of the SF and JM nephrons. These findings show the presence of both axial and internephron heterogeneity of renal gluconeogenesis and suggest the difference in the effects of PTH on the function of SF and JM nephrons.

scholarly journals Growth hormone, cyclic nucleotides and the rapid control of translation in heart muscle

1975 ◽  
Vol 152 (3) ◽  
pp. 583-592 ◽  
Author(s):  
J Mowbray ◽  
J A Davies ◽  
D J Bates ◽  
C J Jones
Keyword(s):  
Growth Hormone ◽  
Protein Synthesis ◽  
Cyclic Amp ◽  
Cyclic Gmp ◽  
Cyclic Nucleotides ◽  
Cyclic Nucleotide ◽  
Precursor Pool ◽  
Growth Hormone Action ◽  
Constant Rate ◽  
The Individual

Perfused rat heart incorporated L-[14C]tyrosine into protein at a constant rate for up to 75 min. A purified bovine growth-hormone preparation (1 mug/ml) stimulated the incorporation to a new constant rate that was more than three times the control rate by 10 min after hormone addition to perfusate. The hormone, however, did not alter the intracellular tracer amino acid pool, and the relationship of this to the aminoacyl-tRNA precursor pool is discussed. It is concluded that the increased incorporation largely reflected a rapid increase in protein synthesis at the ribosomes. Measurements of cyclic nucleotide contents during the perfusion showed that these appeared to vary in a systematic way during the perfusion. This strands in contrast with the constant values given by several other parameters measured in this preparation. Futher, the cyclic nucleotide variation seems to be independent of external effectors. The steady-state performance of the heart correlates more closely the [cyclic AMP]/[cyclic GMP] ratio than with the content of the individual cyclic nucleotides. At 10 min after the addition of growth hormone a slight decrese in cyclic AMP content and a large decrease in cyclic GMP were found, suggesting that the hormone's effect in stimulating protein synthesis may be mediated by a decrease in cyclic nucleotide concentrations or an increase in the [cyclic AMP]/[cyclic |p] ratio. The findings are also consistent with an intracellularly directed role for these nucleotides, and the possibility that the cyclic nucleotide changes are an indirect result of growth-hormone action is discussed.

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