Cell dissociation with papain reduces the density of cGMP-activated channels of the retinal rod.
A proteolytic enzyme, papain, is the enzyme commonly used for dissociation of retinal neurons. To ask whether papain modifies the activity of ion channels, cGMP-activated channels were recorded in inside-out membrane patches excised from the bullfrog rod outer segment, and the activity was compared between cells dissociated using papain and cells dissociated mechanically. While the affinity to cGMP, I-V relation, channel kinetics, and single-channel current amplitude were almost the same in both papain-treated and the control preparations, the total current flowing through the patch membrane of the papain-treated cells was reduced to about 20% of the control, suggesting that papain reduced the density of cGMP-activated channels.
Shen
J
J
Department of Physiology, Keio University School of Medicine, Tokyo, Japan.
Watanabe
S
S
Kaneko
A
A
D000818:Animals; D006152:Cyclic GMP / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D004553:Electric Conductivity; D007473:Ion Channels / Q000187:drug effects* / Q000378:metabolism* / Q000502:physiology; D010206:Papain / Q000494:pharmacology*; D011892:Rana catesbeiana; D012160:Retina / Q000166:cytology / Q000187:drug effects*; D017948:Retinal Rod Photoreceptor Cells / Q000378:metabolism*
D007473:Ion Channels; D010206:Papain; D006152:Cyclic GMP