Inositol transport in preimplantation rabbit embryos: effects of embryo stage, sodium, osmolality and metabolic inhibitors
in ReproductionSearch for other papers by SM Warner in
Current site
Google Scholar
PubMed
Search for other papers by FV Conlon in
Current site
Google Scholar
PubMed
Search for other papers by MT Kane in
Current site
Google Scholar
PubMed
The preimplantation period in the rabbit consists of a 3 day cleavage stage during which the number of cells increases with little change in embryo size, followed by a 3-4 day blastocyst stage during which the inner cell mass, the blastocoel and the trophectodermal layer are formed and the embryo grows rapidly in size and protein content. This study used [(3)H]inositol to investigate the transport of inositol, an essential component of the phosphatidylinositol signal transduction system, over the 6 days of preimplantation development by rabbit embryos. In the presence of 15 micromol inositol l(-1) in the incubation medium, there was a small linear increase in inositol uptake from 0.07 pmol per embryo per h at the one-cell stage (day 1) to 0.135 pmol at the late morula (day 3) stage. Inositol uptake increased to 0.58 pmol per embryo per h for early blastocysts (day 4) and 23.7 pmol for late blastocysts (day 6). There was a significant linear relationship between inositol uptake and blastocyst diameter and surface area. Efflux of inositol from early morulae was minimal (about 1.25% of embryo content per h), whereas efflux from mid-blastocysts (day 5) was much greater (about 15.6% of embryo content per h). Efflux of inositol from both early morulae and mid-blastocysts was increased by decreasing the osmolality of the incubation medium. Varying the osmolality had no effect on inositol uptake up to 2 h. Inositol uptake was dependent on sodium in cleavage-stage embryos but independent of sodium in blastocyst stages. In early morulae, inositol uptake was inhibited by glucose and the sodium-dependent hexose transport inhibitor, phloridzin, but not by the facilitated transport inhibitor, phloretin. Inositol uptake in early morulae was saturable; estimates of 0.227 and 0.288 pmol per morula per h for V(max) and 0.045 and 0.038 micromol l(-1) for K(m) were obtained for sodium-dependent transport in two separate experiments. All of these results are consistent with the hypothesis that transport in cleavage stages occurs via a sodium myo-inositol transporter (SMIT) protein. Uptake in blastocysts was non-saturable. Uptake into blastocysts appeared to take place by a transcellular rather than a paracellular route.
Reproduction is committed to supporting researchers in demonstrating the impact of their articles published in the journal.
The two types of article metrics we measure are (i) more traditional full-text views and pdf downloads, and (ii) Altmetric data, which shows the wider impact of articles in a range of non-traditional sources, such as social media.
More information is on the Reasons to publish page.
| Sept 2018 onwards | Past Year | Past 30 Days | |
|---|---|---|---|
| Full Text Views | 186 | 40 | 1 |
| PDF Downloads | 155 | 66 | 0 |
Online ISSN: 1741-7899
Print ISSN: 1470-1626
Strengthening biomedical communities
to advance science and health
CONTACT US
Bioscientifica Ltd | Starling House | 1600 Bristol Parkway North | Bristol BS34 8YU | UK
Bioscientifica Ltd | Registered in England no 3190519