There certainly appears to be some degree of renal adaptation to hyperkalemia in chronic kidney disease. Early animal studies in which rats were exposed to varying degrees of infused potassium concentrations demonstrate that hyperkalemia dramatically regulates the degree of potassium secretion, primarily via aldosterone-mediated mechanism in the collecting duct. In addition, this 2002 Kidney International review argues that the hyperkalemia seen in CKD is an adaptive, physiologic response, reflecting a new steady state in which extracellular K rises to the level needed to stimulate K excretion so that it matches intake. There is less data as to what adaptive mechanisms are active in the complete absence of renal function, and furthermore, it's hard to know whether or not such adaptations to hyperkalemia would be operative in many ESRD patients where the K fluctuates dramatically with regards to pre- and post-K levels. One might expect different ion channels in the myocardium to be up/downregulated in order to guard against the cardiac effects of hyperkalemia, or perhaps key K transporters in skeletal muscle are upregulated to maintain the plasma K concentration within the appropriate range.
If anybody knows of other relevant studies looking at adaptations to hyperkalemia, let me know.