Effects of endothelial NOS antagonism within the periaqueductal gray on cardiovascular responses and neurotransmission during mechanical, heat, and cold nociception
Abstract
Nitric oxide (NO) is synthesized from L-arginine using NO synthase (NOS) enzyme that exists as 3 isoforms: endothelial (eNOS), neuronal (nNOS), and inducible (iNOS). We examined the role of eNOS within the dorsolateral periaqueductal gray mater (dlPAG) on cardiovascular responses along with glutamate and GABA concentrations during mechanical-, heat-, and cold-induced nociception in anesthetized rats. Mechanical stimulus was applied by a 10-second hindpaw pinch that increased mean arterial pressure (MAP) and heart rate (HR). Bilateral microdialysis of a selective eNOS antagonist, L-N(5)-(1-iminoethyl)ornithine (L-NIO; 10 microM), into the dlPAG had no effect on MAP or HR during a mechanical stimulation. Heat stimulus was generated by immersing a hindpaw metatarsus in a water-bath at 52 degrees C for 10 s which increased glutamate, GABA, MAP and HR. Administration of L-NIO into the dlPAG augmented cardiovascular responses and glutamate increase, but attenuated GABA changes during the heat stimulus. In contrast, application of a cold stimulus by immersing the hindpaw at 10 degrees C for 10 s resulted in decreases in MAP, HR, and glutamate. However, there was an increase in GABA concentration. Following microdialysis of L-NIO into ...Continue Reading
References
Citations
Related Concepts
Related Feeds
Cardiovascular Homeostasis
Cardiovascular regulation and homeostasis is important in maintaining health and dysfunction may lead to cardiovascular diseases. Nitric oxide and vascular endothelium are one of many molecules involved in the homeostatic mechanism. Here is the latest research on cardiovascular homeostasis.
Bradyarrhythmias
Bradyarrhythmias are slow heart rates. Symptoms may include syncope, dizziness, fatigure, shortness of breath, and chest pains. Find the latest research on bradyarrhythmias here.