Alterations in concentrations of cyclic guanosine 3',5'-monophosphate in guinea pig urine during the development of a transplantable leukaemia.

Cyclic guanosine 3',5'-monophosphate (cGMP) concentrations were measured in urine specimens from guinea pigs before and after transplantation of a leukemia. A transient increase in cGMP concentration occurred 3 days after inoculation which preceded any detectable increase in the white blood cell count. This peak in cGMP concentration was found to be very highly significant when compared with fluctuations in urinary cGMP levels in the guinea pigs from transplantation of the leukemia. Inoculation of guinea pigs with irradiated L2C cells suggests that transplantation may cause an initial depression in urine cGMP concentration but no elevated cGMP concentrations were observed in these animals. The results indicate that urine cGMP concentrations may be a useful way of monitoring abnormal cell proliferation.