Koch's postulates and the digitalis-like factor

Abstract

Substantial, but still circumstantial evidence, supports strongly a role for a circulating digitalis-like factor in the pathogenesis of salt-sensitive hypertension. Although supported by many lines of evidence, this intriguing concept remains controversial, in large part because the responsible factor has proven to be very elusive. A very large number of candidates from a wide range of chemical classes have been proposed. Indeed, the large number of candidates, none supported by absolutely definitive evidence, has contributed to the controversy. In this essay, we have attempted to define the information that will be required before a candidate becomes widely accepted. Because the current situation resembles so strikingly the situation late in the nineteenth century--when efforts focused on the attempt to identify a specific micro-organism as the agent responsible for specific disease--we employed Koch's postulates as the organizing principle. The challenge faced by Robert Koch over a century ago is identical to the challenge that we face today.