Role of presympathetic C1 neurons in the sympatholytic and hypotensive effects of clonidine in rats

摘要: The rostral ventrolateral medulla (RVLM) may play an important role in the sympatholytic and hypotensive effects of clonidine. present study examined which type presympathetic RVLM neuron is inhibited by clonidine, whether adrenergic neurons are essential for clonidine-induced sympathoinhibition. In chloralose-anesthetized ventilated rats, clonidine (10 microg/kg iv) decreased arterial pressure (116 +/- 6 to 84 2 mmHg) splanchnic nerve activity (93 3% from baseline). Extracellular recording juxtacellular labeling barosensitive bulbospinal revealed that most cells were (26/28) regardless phenotype [tyrosine hydroxylase (TH)-immunoreactive cells: 48 7%; non-TH-immunoreactive 42 5%], although inhibition was modest compared with observed Depletion catecholaminergic neurons, including 76 5% C1 cells, microinjection saporin anti-dopamine beta-hydroxylase into thoracic spinal cord (levels T2 T4, ng. 200 nl(-1). side(-1)) did not alter or These data show inhibits do appear be systemically administered Instead, effect likely result a combination on multiple cell types both within outside RVLM.