[Changes in renal nerve efferent activity upon stimulation of medullary nuclei with serotonin]

In acute experiments on cats, microinjections of 2 micrograms of serotonin to the nucleus of tractus solitarii and to the ventral reticular nucleus brought about remarkable and consistent changes in renal sympathetic activity. The test nuclei were shown to contain serotoninoceptive neurons. Serotonin activation of the neurons led to the potentiation of efferent activity. The stimulation also had an inhibitory effect on renal sympathetic activity. Microinjections of serotonin to the nucleus of tractus solitarii at the height of the pressor sinocarotid reflex suppressed the sympathetic activity, while the systemic arterial pressure was negligibly changed. The evidence obtained suggests that the effect of intrastructurally injected serotonin on sympathetic renal activity is determined to a considerable degree by the function of the test structures.