Effect of PACAP38 on light chain–induced human TNFα production in rat kidney. κ-Light chain (50 μM) purified from the urine of a patient with multiple myeloma was administered intravenously into a freely moving rat through the chronically implanted jugular cannula. The control animals received the same amount of saline as that of light chain solution. On completion of administration of the light chain or saline over 72 hours the rat was killed to examine the expression of TNFα in the kidney. The level of TNFα in the kidney increased several times as compared with the control level after the treatment. When PACAP38 was intravenously administered with the light chains, the stimulation of TNFα production in the kidney was significantly suppressed. Each value represents the mean ± SE from 4 kidneys. ***P < .001 and **P < .01.