Abstract
Previous studies have shown that inhibition of the renal tubular excretion of N1-methylnicotinamide (NMN) by other rapidly transported organic bases, e.g., tetraethylammonium (TEA), is characterized by immediate onset and reversibility when NMN and the inhibitors are infused into the portal circulation of one kidney in chickens.
Inhibition of NMN transport by a cyanine dye (#863) was gradual and progressive in onset at low infusion loads of the inhibitor, the speed of onset being greatly augmented with higher infusion loads. Reversibility in both cases was gradual rather than immediate, but was more rapid than that previously seen in dogs.
Inhibition of NMN transport in the chicken by most members of a series of polymethylene bis(trialkylammonium) compounds resembled that produced by the cyanine with respect to onset, but reversibility, studied in the case of one compound, was immediate.
The cyanine and the bisquaternaries accumulated in the kidney in high concentration and appeared in the urine only in small amounts. In contrast, the rapidly transportable compound TEA showed little renal accumulation.
One bisquaternary compound, in which all constituents on the quaternary nitrogen were butyl radicals, produced an immediate rapidly reversible inhibition of NMN transport, i.e., an inhibition resembling that produced by rapidly transportable organic bases. Yet this inhibitor was excreted only to a negligible extent.
The implications of a relationship between these various findings is discussed.
Footnotes
- Received December 3, 1959.
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