Summary The responses of the smooth muscle of the capsule and blood vessels of the isolated, perfused human spleen to sympathetic nerve stimulation, adrenaline, noradrenaline, angiotensin, oxytocin, vasopressin, isoprenaline and acetylcholine have been investigated and compared with those of dog spleen. Stimulation of the postganglionic sympathetic nerves to the human spleen at frequencies of 3–10 Hz evoked graded vasoconstriction but very small changes in spleen volume. The injection of adrenaline and noradrenaline in doses of 0·25–25 μg to the human spleen produced graded increases in splenic vascular resistance with very small decreases in spleen volume. Administration of the α‐adrenoceptor blocking drug phenoxybenzamine completely abolished or considerably reduced the vascular responses of the human spleen to sympathetic nerve stimulation or the injection of noradrenaline. The vascular action of adrenaline was often reversed to elicit a vasodilatation after phenoxybenzamine suggesting the presence of β‐adrenoceptors in the vascular bed. This was confirmed by the administration of isoprenaline which induced a marked reduction in vascular resistance of the human spleen. The polypeptides angiotensin and vasopressin induced a marked vasoconstriction in the human spleen without changes in the spleen volume. These effects were uninfluenced by the administration of phenoxybenzamine. The polypeptide oxytocin caused a slight vasodilatation in the human spleen, an effect almost exactly mimicked by the preservative chlorobutanol. Preliminary experiments suggest that noradrenaline is the transmitter released by the postganglionic nerves to the human spleen. These results provide direct evidence that the normal human spleen, unlike that of the dog, does not have a reservoir function. It is suggested that contractions of the enlarged human spleen may occur in various pathological conditions.

Lymphocytic adenohypophysitis can cause pituitary expansion and hypopituitarism closely mimicking the features of a pituitary adenoma. Discrimination between these two conditions is of importance since, despite the similarity of their presentation, there are significant differences in pathophysiology. In contrast to pituitary adenoma, lymphocytic adenohypophysitis occurs almost exclusively in young women in relation to pregnancy, there is a preference for destruction of ACTH and TSH secreting cells and computed tomographic scanning shows uniform contrast enhancement in a proportion of cases. There is, as yet, no proven specific non-surgical treatment. There are anecdotal reports of a beneficial effect of steroids but there is also evidence that spontaneous resolution may occur. We have reviewed the literature and report two new cases of lymphocytic adenohypophysitis both of whom exhibited early striking diffuse homogeneous contrast enhancement on magnetic resonance imaging scanning which we suggest may be a diagnostic feature of this condition.

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