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Sulfur dioxide in the caudal ventrolateral medulla reduces blood pressure and heart rate in rats via the glutamate receptor and NOS/cGMP signal pathways

CAI Hong-Yan¹, LI Bin², DANG Lei², YANG Jing¹, MAN Ke¹, DONG Chen-Ming¹, LU Yan^3,*

¹Department of Critical Care, Lanzhou University Second Hospital, Lanzhou 730000, China；²Department of General Surgery, Department of Interventional Radiology, The First Hospital of Lanzhou University, Lanzhou 730000, China；³Department of Clinical Laboratory, Gansu Provincial Hospital, Lanzhou 730000, China

Abstract

This study was designed to investigate the cardiovascular effects of sulfur dioxide (SO2) in the caudal ventrolateral medulla (CVLM) of anesthetized rats and its mechanism. Different doses of SO2 (2, 20, 200 pmol) or artificial cerebrospinal fluid (aCSF) were injected into the CVLM unilaterally or bilaterally, and the effects of SO2 on blood pressure and heart rate of rats were observed. In order to explore the possible mechanisms of SO2 in the CVLM, different signal pathway blockers were injected into the CVLM before the treatment with SO2 (20 pmol). The results showed that unilateral or bilateral microinjection of SO2 reduced blood pressure and heart rate in a dose-dependent manner (P < 0.01). Moreover, compared with unilateral injection of SO2 (2 pmol), bilateral injection of 2 pmol SO2 produced a greater reduction in blood pressure. Local pre-injection of the glutamate receptor blocker kynurenic acid (Kyn, 5 nmol) or soluble guanylate cyclase (sGC) inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ, 1 pmol) into the CVLM attenuated the inhibitory effects of SO2 on both blood pressure and heart rate. However, local pre-injection of nitric oxide synthase (NOS) inhibitor NG-Nitro-L-arginine methyl ester (L-NAME, 10 nmol) only attenuated the inhibitory effect of SO2 on heart rate but not blood pressure. In conclusion, SO2 in rat CVLM has cardiovascular inhibitory effects, and its mechanism is related to the glutamate receptor and NOS/cGMP signal pathways.

Key words: Blood pressure; heart rate; sulfur dioxide; glutamate receptors; NOS/cGMP signal pathway; caudal ventrolateral medulla

Received: 　　Accepted:

Corresponding author: 鲁彦　　E-mail:

DOI: 10.13294/j.aps.2023.0011

Citing This Article：

CAI Hong-Yan, LI Bin, DANG Lei, YANG Jing, MAN Ke, DONG Chen-Ming, LU Yan. Sulfur dioxide in the caudal ventrolateral medulla reduces blood pressure and heart rate in rats via the glutamate receptor and NOS/cGMP signal pathways. Acta Physiol Sin 2023; 75 (1): 27-35 (in Chinese with English abstract).