1. Hypertension is a complication of autologous bone marrow transplantation when therapy includes multiple alkylating agents. We have sought to identify the factors underlying this hypertension. We measured weight, serum creatinine, plasma renin activity, aldosterone and digoxin-like immunoreactive factor (DL1F), by digoxin radioimmunoassay, in 18 patients. Plasma catecholamines were also measured in five patients.
2. Of the 18 patients studied, 15 became hypertensive. The variable most consistently associated with these individuals' hypertension was DLIF activity which was increased in 14 of the 15 hypertensive patients (P = 0.055, Fisher exact test). Serum creatinine was increased at some point in seven of the 15 hypertensive patients, weight was increased in five and plasma renin activity and aldosterone were increased in one. Catecholamines were not increased in any of the five patients in which they were measured.
3. The association between changes in mean arterial pressure (MAP) and changes in DL1F for the group as a whole was assessed by analysing one data pair per patient, representing the maximal MAP. This correlation was significant (r = 0.75, P = 0.001).
4. Within individual patients, changes in MAP and changes in serum DLIF concentrations were significantly correlated (r > 0.50, P < 0.05) in six of 15 hypertensive patients.
5. Digitalis-like factor (DLF) was measured by inhibition of (Na+,K+)-adenosine 5′-triphosphatase in five patients and DLF and DLIF were significantly correlated (r = 0.81, P = 0.0001). DLF and MAP were also significantly correlated (r = 0.59, P = 0.002).
6. This represents the first longitudinal study of the relationship between DLIF and blood pressure in hypertensive individuals, and the results suggest that DLIF may contribute to the increased blood pressure in some of these subjects.