Jugular lymph flow of anesthetized rabbits in response to infusion of mannitol solutions differing in osmolarity were measured. Either an isotonic (310 mosmol), hypotonie (100 mosmol), or hypertonic (605 mosmol) mannitol solution was infused into either the internal carotid artery (ICA) or the right lateral ventricle (RLV). Lymph was collected continuously and measured over a 60 min preinfusion period, as well as during mannitol infusion and intermittent recovery periods. The mean peak flow rates of hypertonic infusion for the first 30 min via ICA and RLV were 2.2 ± 0.4 (12% decrease) and 5.0 ± 1.0 μl/min (72% ncrease), over those of isotonic infusates which were 2.5 ± 0.3 μl/min (via ICA) and 2.9 ± 0.5 μl/min (via RLV), respectively. In contrast, lymph flow rates of hypotonie infusate for the first 30 min via ICA and RLV were 3.9 ± 0.8 μl/min and 2.3 ± 0.4 μl/min, respectively. A decrease both in intracranial pressure and in lymph flow following hypertonic mannitol infusion via ICA were observed. However, intracranial pressure and lymph formation were increased following hypertonic infusion via RLV. The results indicate that the changes in jugular lymph flow could be affected by the changing in osmolarity of mannitol infusate.
