In vitro studies on active calcium absorption from ovine rumen

1999 ◽  
Vol 169 (7) ◽  
pp. 487-494 ◽  
Author(s):  
B. Schröder ◽  
S. Vössing ◽  
G. Breves
Keyword(s):  
Calcium Absorption ◽  
In Vitro Studies ◽  
Active Calcium

In vitro studies on calcium absorption from the gastrointestinal tract in␣small ruminants

1997 ◽  
Vol 167 (1) ◽  
pp. 43-51 ◽  
Author(s):  
Bernd Schröder ◽  
Ina Rittmann ◽  
Ernst Pfeffer ◽  
Gerhard Breves
Keyword(s):  
Gastrointestinal Tract ◽  
Calcium Absorption ◽  
Small Ruminants ◽  
In Vitro Studies

Glucose enhancement of transcellular calcium transport in the intestine

1988 ◽  
Vol 255 (3) ◽  
pp. G339-G345 ◽  
Author(s):  
K. M. Carroll ◽  
R. J. Wood ◽  
E. B. Chang ◽  
I. H. Rosenberg
Keyword(s):  
Calcium Transport ◽  
Calcium Uptake ◽  
Calcium Absorption ◽  
Membrane Integrity ◽  
Calcium Flux ◽  
Calcium Efflux ◽  
Cell Membrane Integrity ◽  
Active Calcium ◽  
Altered Cell

Glucose stimulates calcium transport in vitro in rat duodenal tissue and isolated enterocytes. Under short-circuited conditions, glucose increased mucosal to serosal calcium flux (JCa(m----s)) without altering serosal to mucosal calcium flux (JCa(s----m)) in the duodenum, the primary site of active calcium absorption in the rat small intestine. The half-maximal dose (ED50) of the glucose stimulatory effect was less than 1 mM, and an increase in JCa(m----s) of 80% over control was seen at a glucose concentration of 50 mM. Glucose did not increase calcium flux in the ileum where active calcium absorption is minimal. Glucose stimulated net calcium uptake by 35% in isolated duodenal enterocytes. Glucose did not alter calcium efflux from preloaded enterocytes suspended in calcium-free buffer. Glucose enhancement of net calcium uptake in enterocytes was not caused by altered cell membrane integrity or functional viability. The nonmetabolizable glucose analogue alpha-methylglucoside did not stimulate calcium transport. Our findings suggest that glucose can stimulate intestinal calcium absorption, at least partially, by enhancing transcellular calcium transport and that cellular glucose metabolism is necessary for stimulation of this route of calcium transport.

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.

Influence of vitamin D on calcium absorption in the chick

1962 ◽  
Vol 203 (3) ◽  
pp. 497-505 ◽  
Author(s):  
J. D. Sallis ◽  
E. S. Holdsworth
Keyword(s):  
Vitamin D ◽  
Small Intestine ◽  
Calcium Transport ◽  
Calcium Absorption ◽  
Metabolic Inhibitors ◽  
Hydroxyl Groups ◽  
Oxidation Reduction ◽  
Active Calcium

The site of absorption of Ca45 was studied in rachitic chicks and rachitic chicks given vitamin D3. Vitamin D3 markedly increases absorption from the small intestine and, in vivo, similar amounts of calcium are absorbed along the entire small intestine. With everted gut sacs, the distal third of the small intestine transported much more calcium than did the duodenal and middle sections. Thus, interpretations of in vitro results may not always depict the natural in vivo process. Vitamin D2 had little activity in the chick, but AT-10 series 2 and AT-10 series 3 were almost as active as vitamin D3 for calcium transport. These results suggest an "active carrier" may be formed by addition of hydrogen or hydroxyl groups to the opened ring B of vitamin D, giving a carrier capable of reversible oxidation-reduction or keto-enol tautomerism. Using metabolic inhibitors, active calcium transport in vitro relied on glycolysis for its energy supply. The transport was independent of the sodium pump.

In vitro - studies with antler bone cells: Structure forming capacity, osteocalcin production and influence of sex steroids

2006 ◽  
Vol 15 (04) ◽  
pp. 245-257 ◽  
Author(s):  
H. J. Rolf ◽  
K. G. Wiese ◽  
H. Siggelkow ◽  
H. Schliephake ◽  
G. A. Bubernik
Keyword(s):  
Sex Steroids ◽  
Bone Cells ◽  
In Vitro Studies ◽  
Osteocalcin Production

In Vitro Studies on the Mechanism of the Antifibrino-lytic Action of E-Aminocaproic Acid (EACA)

1968 ◽  
Vol 19 (03/04) ◽  
pp. 584-592 ◽  
Author(s):  
Hanna Lukasiewicz ◽  
S Niewiarowski
Keyword(s):  
Aminocaproic Acid ◽  
Test Tube ◽  
In Vitro Studies ◽  
Lytic Action ◽  
Human Plasminogen ◽  
Experimental Findings ◽  
Fibrin Clots

Summary and Conclusion1. It has been found that EACA does not inhibit activation of human plasminogen into plasmin by SK and UK in a concentration of 5 × 10–2 M. The activation of bovine plasminogen by SK and UK is inhibited by this concentration of EACA but not by a lower one.2. EACA in concentrations of 1,5 × 10–1 – 10–4 M does not inhibit casein proteolysis by plasmin. The proteolysis of fibrinogen and fibrin measured by the release of TCA soluble tyrosine is inhibited by EACA in concentrations of 1,5 × 10–1 – 10–2 M.3. The lysis of non-stabilized clots by plasmin measured in a test tube was inhibited by an EACA concentration of 5 × 10–3 – 5 × 10–4 M. The lysis of stabilized clots by plasmin was inhibited by an EACA concentration of 10–5 M.4. On the basis of experimental findings and data given in literature the authors postulate that the mechanism of the antifibrinolytic effects of EACA consists mainly in a modification of plasmin action on fibrin. These effects are dependent on the structure of the fibrin clots.

The Venom of the Boomslang (Dispholidus Typus): In Vivo and in Vitro Studies

1969 ◽  
Vol 21 (02) ◽  
pp. 234-244 ◽  
Author(s):  
N Mackay ◽  
J.C Ferguson ◽  
Antonia Bagshawe ◽  
A.T.T Forrester ◽  
G.P Mcnicol
Keyword(s):  
In Vitro Studies

SummaryAn account is given of the effects of boomslang venom in man. Evidence was found of a fibrinolytic state apparently secondary to the coagulant action of the venom. These features rapidly responded to the administration of specific antivenom. In vitro studies, using a homogenate of boomslang parotids, confirmed the coagulant properties of the venom and showed them to be of much greater potency than the proteolytic actions.

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