Endogenous prolactin modulated the calcium absorption in the jejunum of suckling rats

2005 ◽  
Vol 83 (7) ◽  
pp. 595-604 ◽  
Author(s):  
Suwimol Amnattanakul ◽  
Narattaphol Charoenphandhu ◽  
Liangchai Limlomwongse ◽  
Nateetip Krishnamra
Keyword(s):  
Tight Junction ◽  
Physiological Condition ◽  
Calcium Absorption ◽  
Sodium Concentration ◽  
Calcium Fluxes ◽  
Suckling Rats ◽  
Control Value ◽  
Intestinal Segments ◽  
Old Rats ◽  
Calcium Secretion

Prolactin has been reported to stimulate intestinal calcium absorption in young and mature, but not aging rats. The present study was performed on suckling rats to elucidate the actions of endogenous prolactin on calcium absorption in various intestinal segments. Before measuring the calcium fluxes, 9-day-old rats were administered for 7 days with 0.9% NaCl, s.c. (control), 3 mg/kg bromocriptine, i.p., twice daily to abolish secretion of endogenous pro lac tin, or bromocriptine plus exogenous 2.5 mg/kg prolactin, s.c. Thereafter, the 16-day-old rats were experimented upon by instilling the 45Ca-containing solution into the intestinal segments. The results showed that, under a physiological condition, the jejunum had the highest rate of calcium absorption compared with other segments (1.4 ± 0.35 µmol·h–1·cm–1, p < 0.05). The duodenum and ileum also manifested calcium absorption, whereas the colon showed calcium secretion. Lack of endogenous prolactin decreased lumen-to-plasma and net calcium fluxes in jejunum from 2.07 ± 0.31 to 1.19 ± 0.12 and 1.40 ± 0.35 to 0.88 ± 0.18 µmol·h–1·cm–1 (p < 0.05), respectively, and exogenous prolactin restored the jejunal calcium absorption to the control value. Endogenous prolactin also had an effect on the duodenum but, in this case, exogenous prolactin did not reverse the effect of bromocriptine. However, neither ileal nor colonic calcium fluxes were influenced by prolactin. Because luminal sodium concentration has been demonstrated to affect calcium absorption in mature rats, the effect of varying luminal sodium concentrations on calcium fluxes in suckling rats was evaluated. The jejunum was used due to its highest rate of calcium absorption. After filling the jejunal segments with 124 (control), 80, 40 mmol/L Na+-containing or Na+-free solution, increases in calcium absorption were found to be inversely related to luminal sodium concentrations in both control and bromocriptine-treated rats. The plasma concentration of 45Ca under luminal sodium free condition was also higher than that of the control condition (2.26% ± 0.07% vs. 2.01% ± 0.09% administered dose, p < 0.05). However, 3H-mannitol, a marker of the widening of tight junction that was introduced into the lumen, had a stable level in the plasma during an increase in plasma 45Ca, suggesting that the widening of tight junction was not required for enhanced calcium absorption. In conclusion, calcium absorption in suckling rats was of the highest rate in the jejunum where endogenous prolactin modulated calcium absorption without increasing the paracellular transport of mannitol. Key words: calcium absorption, intestinal segments, prolactin, suckling rats.

Acute effects of prolactin on passive calcium absorption in the small intestine by in vivo perfusion technique

1998 ◽  
Vol 76 (2) ◽  
pp. 161-168 ◽  
Author(s):  
Nateetip Krishnamra ◽  
Yinglak Wirunrattanakij ◽  
Liangchai Limlomwongse
Keyword(s):  
Body Weight ◽  
Calcium Absorption ◽  
Dry Weight ◽  
Sodium Concentration ◽  
Plasma Calcium ◽  
Calcium Flux ◽  
Proximal Jejunum ◽  
Perfusion Technique ◽  
Calcium Fluxes

The acute effect of intraperitoneally administered prolactin (0.2, 0.4, and 0.6 mg/kg body weight) on passive calcium transport in duodenum, proximal jejunum, and ileum of sexually mature female Wistar rats was investigated by using an in vivo perfusion technique. Test solution containing (in mM) NaCl, 100; KCl, 4.7; MgSO4, 1.2; CaCl2, 20; D-glucose, 11; sodium ferrocyanide (Na4Fe(CN)6), an index of net water transport, 20; and 0.7 µCi 45CaCl2 (1 Ci = 37 GBq) was perfused through the 10-cm intestinal loop for 60 min. Results showed that 0.4 mg prolactin/kg body weight significantly increased duodenal net Ca absorption (net Ca) from 23.81 ± 1.84 to 30.56 ± 1.57 mmol/g dry weight (p < 0.05) by stimulating the lumen to plasma calcium flux (CaL-P). The jejunum responded to 0.2, 0.4, and 0.6 mg prolactin/kg body weight by reversing from net Ca absorption of 18.60 ± 1.70 mmol/g dry weight to net secretion of -3.30 ± 1.56, -10.39 ± 2.21, and -11.79 ± 2.04 mmol/g dry weight (p < 0.01), respectively, as a result of a dose-dependent increase in plasma to lumen calcium flux (CaP-L). Calcium fluxes in the ileum on the other hand did not respond to prolactin. There was a close correlation between net water flux and net calcium flux in all three intestinal segments under basal condition regardless of the luminal sodium concentration. However, this correlation was lost after prolactin administration, which while having no effect on net water flux, altered the duodenal and jejunal calcium fluxes. By varying the luminal concentration of sodium, it was found that the stimulatory effect of 0.4 mg prolactin/kg body weight on the duodenal CaL-P was reduced when compared with control, i.e., 17.84 ± 0.91 vs. 26.64 ± 1.05 mmol/g dry weight at a sodium concentration of 180 mM, and 14.48 ± 0.99 vs. 20.12 ± 1.34 mmol/g dry weight at a sodium concentration of 140 mM. At a sodium concentration of 80 mM, the prolactin effect was absent. Since duodenal Na+-K+ ATPase activity was increased by prolactin from 3.77 ± 0.16 to 4.95 ± 0.30 µmol Pi ·mg-1 protein ·h-1 (p < 0.05), sodium dependency of the prolactin-enhanced lumen to plasma calcium flux may be related to both sodium-induced water flow and calcium-sodium exchange across the basolateral membrane. Thus, it was postulated that under basal condition, net calcium transport in the small intestine occurred with the sodium-induced water transport along the paracellular pathway. However, after prolactin administration, this association was lost. Prolactin-enhanced lumen to plasma calcium flux in the duodenum was sodium dependent and involved the Na+-K+ ATPase activity. In the proximal jejunum, prolactin stimulated plasma to lumen calcium flux, but the mechanism was not known.Key words: calcium absorption, calcium fluxes, Na-K ATPase, perfusion technique, prolactin.

Calcium transport in turtle bladder

1987 ◽  
Vol 253 (6) ◽  
pp. R917-R921
Author(s):  
S. Sabatini ◽  
N. A. Kurtzman
Keyword(s):  
Calcium Transport ◽  
Calcium Absorption ◽  
Short Circuit ◽  
Open Circuit ◽  
Calcium Flux ◽  
Bladder Epithelium ◽  
Control Value ◽  
Sodium Calcium ◽  
Turtle Bladder ◽  
Absorptive Flux

Unidirectional 45Ca fluxes were measured in the turtle bladder under open-circuit and short-circuit conditions. In the open-circuited state net calcium flux (JnetCa) was secretory (serosa to mucosa) and was 388.3 +/- 84.5 pmol.mg-1.h-1 (n = 20, P less than 0.001). Ouabain (5 X 10(-4) M) reversed JnetCa to an absorptive flux (serosal minus mucosal flux = -195.8 +/- 41.3 pmol.mg-1.h-1; n = 20, P less than 0.001). Amiloride (1 X 10(-5) M) reduced both fluxes such that JnetCa was not significantly different from zero. Removal of mucosal sodium caused net calcium absorption; removal of serosal sodium caused calcium secretion. When bladders were short circuited, JnetCa decreased to approximately one-third of control value but remained secretory (138.4 +/- 54.3 pmol.mg-1.h-1; n = 9, P less than 0.025). When ouabain was added under short-circuit conditions, JnetCa was similar in magnitude and direction to ouabain under open-circuited conditions (i.e., absorptive). Tissue 45Ca content was approximately equal to 30-fold lower when the isotope was placed in the mucosal bath, suggesting that the apical membrane is the resistance barrier to calcium transport. The results obtained in this study are best explained by postulating a Ca2+-ATPase on the serosa of the turtle bladder epithelium and a sodium-calcium antiporter on the mucosa. In this model, the energy for calcium movement would be supplied, in large part, by the Na+-K+-ATPase. By increasing cell sodium, ouabain would decrease the activity of the mucosal sodium-calcium exchanger (or reverse it), uncovering active calcium transport across the serosa.

RENAL CLEARANCE OF SODIUM AND POTASSIUM IN HYPOTHERMIA

1962 ◽  
Vol 40 (1) ◽  
pp. 113-122 ◽  
Author(s):  
G. S. Kanter
Keyword(s):  
Artificial Respiration ◽  
Plasma Potassium ◽  
Sodium Concentration ◽  
Plasma Sodium ◽  
Renal Tubules ◽  
Sodium Pentobarbital ◽  
Clearance Ratio ◽  
Control Value ◽  
The Difference ◽  
Sodium And Potassium

The handling of sodium and potassium by the renal tubules at various levels of hypothermia was studied. Fourteen dogs were anesthetized with 30 mg/kg sodium pentobarbital. After suitable control clearance measurements, the rectal temperature was lowered progressively by ice-packing to about 25 °C while renal clearances were continuously measured. Artificial respiration was not used. No change in plasma sodium was detected but plasma potassium fell significantly from a control value of 4.1 ± 0.09 meq/1. at 38 °C to 3.4 ± 0.12 meq/1. at 25 °C. Urine sodium concentration fell during exposure to cold while potassium concentration increased slightly. In spite of the marked fall in glomerular nitration rate (69.0 ± 3.1 ml/minute control to 17.0 ± 3.6 ml/minute at 25 °C) the final urine flow at 25 °C was slightly greater than that of control. The clearance ratios (in percentage) increased significantly, reflecting the marked decrease in tubular reabsorption: water, 0.49 ± 0.05 at 38 °C to 2.02 ± 0.25 at 25 °C; sodium, 0.47 ± 0.12 to 1.13 ± 0.27; potassium, 18.0 ± 2.6 to 54.0 ± 12.0. The difference in clearance ratio alterations is a reflection of the dissimilar effect of hypothermia on particular renal regulations.

REVERSAL OF BETAMETHASONE-INDUCED INHIBITION OF INTESTINAL CALCIUM ABSORPTION BY 1α-HYDROXYCHOLECALCIFEROL

1978 ◽  
Vol 78 (2) ◽  
pp. 187-194 ◽  
Author(s):  
J. FOX ◽  
A. D. CARE ◽  
D. H. MARSHALL
Keyword(s):  
Absorption Coefficient ◽  
Oral Administration ◽  
Intestinal Absorption ◽  
Calcium Absorption ◽  
Mean Value ◽  
Intestinal Calcium Absorption ◽  
Control Value ◽  
Isotope Technique ◽  
Intravenous And Oral Administration ◽  
Double Isotope

SUMMARY The intestinal absorption of calcium has been studied in conscious, unstressed pigs, using a modification of the double isotope technique. The oral administration of betamethasone (1 mg/day) to four pigs (25–33 kg) for 4 weeks reduced the calcium absorption coefficient, calculated after the intravenous and oral administration of 47Ca2+, by a mean value of 66%. The oral administration of 1α-hydroxycholecalciferol (2 μg/day) in combination with betamethasone (1 mg/day) for a further 4 weeks returned the absorption coefficient to the control value.

scholarly journals DISPOSITION OF INTRAPERITONEALLY INJECTED CALCIUM-45 IN SUCKLING RATS

1958 ◽  
Vol 41 (4) ◽  
pp. 767-782 ◽  
Author(s):  
Felix Bronner
Keyword(s):  
Soft Tissue ◽  
Time Course ◽  
Specific Activity ◽  
Empirical Equations ◽  
Relative Order ◽  
Internal Organs ◽  
Suckling Rats ◽  
Old Rats ◽  
Tissue Compartments

The time course of the concentration of radiocalcium was studied in the serum, skeleton, pelt, muscles, and pooled internal organs of 10-day-old rats. Within 10 hours of injection, the specific activity of the tissue groups exceeded the specific activity of the serum and remained above it during the period studied (120 hours). Chemical and autoradiographic analyses showed how rapidly most of the injected Ca45 found its way into the skeleton. A model was constructed with the assumption that the skeleton constitutes an essentially irreversible reservoir for the tracer in a multicompartment system in which the blood is the central or feeding compartment. The rate of transfer of the tracer from the soft tissue compartments to the serum was calculated from the equation See PDF for Equation in which C = concentration in serum (expressed as a series of exponential terms) C' = concentration in a given soft tissue Substitution in the integrated form of this equation yielded equations which had the major properties of the empirical equations fitted to the experimental points. The relative order of transfer constants (k'–1) was: organs ≥ pelt &gt; muscle.

scholarly journals Dietary protein increases intestinal calcium absorption in part by increasing tight junction expression of Claudin‐2

2011 ◽  
Vol 25 (S1) ◽  
Author(s):  
Erin Gaffney‐Stomberg ◽  
Carrie Cucchi ◽  
Ben‐hua Sun ◽  
Amy Bataille ◽  
Larry Renfro ◽  
...  
Keyword(s):  
Tight Junction ◽  
Dietary Protein ◽  
Calcium Absorption ◽  
Intestinal Calcium Absorption

Effects of somatostatin on intestinal calcium transport in the rat

1981 ◽  
Vol 241 (3) ◽  
pp. G215-G221
Author(s):  
M. J. Favus ◽  
M. Berelowitz ◽  
F. L. Coe
Keyword(s):  
Tissue Concentration ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Strongly Correlated ◽  
Dihydroxyvitamin D3 ◽  
Intestinal Segments ◽  
Absorptive Flux ◽  
Calcium Secretion ◽  
Stimulation Of

The addition of somatostatin (SRIF) to rat descending colon in vitro increased the calcium secretory flux from serosa to mucosa (Js leads to m) and reduced tissue short-circuit current (Isc) but did not alter the absorptive flux from mucosa to serosa (Js leads to m). Js leads to m increased by 37% at 10(-9) M SRIF and by 48% at 10(-6) M. The response to SRIF was not altered by 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], and SRIF did not interfere with stimulation of calcium Jm leads to s by 1,25(OH)2D3. Removal of sodium from the buffer abolished the stimulation of Js leads to m by SRIF without reducing basal Js leads to m. Secretory fluxes of mannitol and calcium were strongly correlated in the presence and absence of SRIF, suggesting that SRIF stimulates a paracellular transepithelial pathway for calcium. In the duodenum, SRIF altered neither calcium Js leads to m nor Isc. In the ileum, calcium Js leads to m increased and Isc decreased, as in the colon, but only by 28 and 12%, respectively. The maximal change in calcium Js leads to m caused by SRIF in these three intestinal segments was negatively correlated with the tissue concentration of immunoreactive SRIF. These results suggest that intestinal calcium secretion could, in part, be regulated by intestinal SRIF.

A bioenergetic explanation for the selective vulnerability of renal medullary tubules to hypoxia

1988 ◽  
Vol 75 (3) ◽  
pp. 323-330 ◽  
Author(s):  
Shozo Torikai
Keyword(s):  
Collecting Duct ◽  
Sodium Concentration ◽  
Selective Vulnerability ◽  
Thick Ascending Limb ◽  
Atp Content ◽  
High Sodium ◽  
Control Value ◽  
Chemical Hypoxia ◽  
Atp Levels ◽  
Chemically Induced

1. In order to explain the vulnerability of medullary thick ascending limb of Heme's loop (mTAL) during hypoxia, adenosine 5′-triphosphate (ATP) content was measured in isolated rat mTAL cells during control conditions and chemically induced hypoxia and compared with those in medullary collecting duct (MCD) cells. 2. Basal ATP levels in mTAL and MCD were estimated as 3.6 and 2.1 mmol/l, respectively. Antimycin A (5 μmol/l) decreased the ATP content by 41% of the control value in the mTAL cells, but failed to reduce that of the MCD cells. Administration of sodium cyanide (5 mmol/l) drastically depleted ATP in the mTAL cells within 5 min (2–3% of control). On the other hand, ATP levels in MCD cells were sustained for at least 60 min after cyanide administration (64% of control). 3. When tubules were made permeable to sodium by the addition of nystatin, the effects of chemical hypoxia on the cell ATP levels were intensified in both segments, and this was partially blocked by pretreatment with ouabain, or by lowering the sodium concentration of the medium. 4. Higher doses of nystatin in mTAL caused a reduction in ATP levels even under control conditions, but its effect was prevented in low sodium medium. 5. The present study suggests that cell ATP levels can be altered by sodium, potassium-dependent adenosine triphosphatase activity, and that due to their high sodium-transporting activity, mTAL cells are more sensitive to reductions in ATP levels during hypoxia than are MCD cells.

Acute effect of prolactin on active calcium absorption in rats

1995 ◽  
Vol 73 (8) ◽  
pp. 1185-1189 ◽  
Author(s):  
Nateetip Krishnamra ◽  
Premthip Taweerathitam
Keyword(s):  
Active Transport ◽  
Calcium Absorption ◽  
Intraperitoneal Administration ◽  
Acute Effect ◽  
In Vitro Experiment ◽  
Everted Gut Sac ◽  
Active Calcium ◽  
Old Rats ◽  
Sexually Mature

Acute effect of prolactin on active calcium absorption was investigated by using the in vitro everted gut sac technique. An intraperitoneal administration of a pharmacological dose of 0.02 mg prolactin/100 g body weight 5 or 10 min before the in vitro experiment significantly increased the active calcium transport (represented by the ratio of serosal to mucosal 45Ca concentration) only in the duodenum, not in other segments. This prolactin-induced duodenal active transport was seen in 8-week-old sexually mature rats but not in 3-week-old weaned, 5-week-old young, or > 15-month-old rats. Enhanced apical uptake of 45Ca in 2 min by the oil-filled everted duodenal sac from rats that received prolactin 5 and 10 min prior to the experiment further supported the speculation that prolactin could acutely alter the duodenal epithelial handling of calcium.Key words: active transport, calcium, everted gut sac, intestinal absorption, prolactin.

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