2-Hydroxypropyl-beta-cyclodextrin removes all-trans retinol from frog rod photoreceptors in a concentration-dependent manner.
OBJECTIVE
To determine whether a nonprotein lipophilic carrier, 2-hydroxypropyl-beta-cyclodextrin (HP-beta-CD), can remove all-trans retinol from rod photoreceptor outer segments. All-trans retinol is generated in rod outer segments after light exposure. It is highly insoluble, and its efficient transport across extra- and intracellular aqueous space requires specialized carriers.


METHODS
Experiments were carried out with isolated frog rod photoreceptor cells. The removal of all-trans retinol by different concentrations of this carrier was measured by imaging its fluorescence in single-rod photoreceptors.


RESULTS
HP-beta-CD concentrations >0.3 mM significantly increased the rate of all-trans retinol removal. The rate of removal increased linearly with carrier concentration, with a slope of 0.0058 min(-1)/mM.


CONCLUSIONS
The effectiveness of HP-beta-CD shows that a specialized interaction with the cell membrane is not necessary for the efficient transfer of all-trans retinol between the cell membrane and the carrier. The transfer occurs through a collision-based mechanism, as indicated by the linear increase of the rate of removal with the carrier concentration.
Johnson
Daniel
D
Department of Physics, College of Charleston, Charleston, South Carolina 29425, USA.
Chen
Chunhe
C
Koutalos
Yiannis
Y
D000073738:2-Hydroxypropyl-beta-cyclodextrin; D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004337:Drug Carriers / Q000008:administration & dosage / Q000494:pharmacology*; D005453:Fluorescence; D066298:In Vitro Techniques; D011894:Rana pipiens; D012374:Rod Cell Outer Segment / Q000378:metabolism*; D014801:Vitamin A / Q000378:metabolism*; D047392:beta-Cyclodextrins / Q000008:administration & dosage / Q000494:pharmacology*
D004337:Drug Carriers; D047392:beta-Cyclodextrins; D014801:Vitamin A; D000073738:2-Hydroxypropyl-beta-cyclodextrin