Intracarotid injection of endothelin-1 facilitates the activity of rostral ventrolateral medullary neurons via area postrema in rats.
To observe the effect of intracarotid administration of endothelin (ET-1) on electrical activity of neurons within rostral ventrolateral medulla (RVLM) region, 87 spontaneous active units were extracellularly recorded in 35 Sprague-Dawley rats with sino-aortic denervation. The results obtained are as follows. (1) Intracarotid administration of ET-1 (0.3 nmol/kg) increased the discharge firing rate from 17.8 +/- 1.5 to 20.9 +/- 1.4 spikes/s (P < 0.01) in 30 out of 36 RVLM neurons, while blood pressure and heart rate had no significant change. (2) BQ-123 (0.67 nmol/kg), a selective ETA blocker, completely blocked the facilitatory effects of ET-1 in 11 out of 14 units. (3) In 10 out of 11 units, glibenclamide (3.3 nmol/kg), a blocker of ATP-sensitive potassium channel, had no effect on the action of ET-1. (4) After ablation of area postrema (AP), the facilitatory action of intracarotid administration of ET-1 on 19 units of RVLM was abolished, while in 7 units of sham ablation animals the response of neurons to ET-1 remained unchanged. Taken together, intracarotid-administered ET-1 may act on the ETA receptors in neurons of AP, thereby resulting in the facilitating effect on RVLM neurons through the efferent projection of AP.
Li
D P
DP
Department of Physiology, Institute of Basic Medicine, Hebei Medical University, Shijiazhuang 050017.
He
R R
RR
D000818:Animals; D002339:Carotid Arteries; D002346:Carotid Sinus / Q000502:physiology*; D004594:Electrophysiology; D065128:Endothelin Receptor Antagonists; D019332:Endothelin-1 / Q000494:pharmacology*; D007269:Injections, Intra-Arterial; D008297:Male; D008526:Medulla Oblongata / Q000502:physiology*; D009474:Neurons / Q000502:physiology; D010456:Peptides, Cyclic / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley
D065128:Endothelin Receptor Antagonists; D019332:Endothelin-1; D010456:Peptides, Cyclic; C072247:cyclo(Trp-Asp-Pro-Val-Leu)