On Mon, 12 Feb 1996, He, X H wrote:
 
> I am now engaged in studying the phagosytosis by confocal imaging with
> Fluosphere as a probe. I want to known whether Amiloride is a specific
> macropinocytosis inhibitor without any other significant effect on the
> cell function. If you know something about this chemical, please tell me
> by email or post on this board. Your help will be very appreciated.
>
> He Xian Hui
> Department of Physiology
> The Chinese University of Hong Kong
> Shatin, NT, Hong Kong
 
Amiloride inhibits many sodium-dependent processes, at different
concentrations. Low micromolar (1-10) inhibits some sodium channels, high
micromolar (100-500) will inhibit sodium hydrogen exchangers (all
isoforms). Once in the millimolar concentration range, all Hell breaks
loose (inhibition of sodium-dependent glucose transport, protein
synthesis, weak acid action as protonophore/uncoupler, etc). I don't know
the concentration range for effects on Na/Ca exchange.
 
Best bet is to use it at low (sub millimolar) concentrations and check to
see if effects are sodium-dependent. At least that will tell you what
manner of beast you are working with. Dale Benos wrote a nice review in
Am. J. Physiol. on the transport effects of amiloride back in the dark
ages (early 1980's I think).
 
Good luck. Chip
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  Chip Montrose
   Johns Hopkins University     tel: 410-955-9681
    Ross 930                      FAX: (410) 955-9677
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