Cardiopulmonary response to vasopressin-induced activation on V1A receptors in the lateral ventrolateral medulla in the rat.
The aim of the study was to examine whether or not arginine vasopressin (AVP) might modulate cardiopulmonary functions by acting on the lateral area of the ventrolateral medulla (VLM) in the rat. The rat was anesthetized, bilaterally vagotomized, paralyzed, ventilated, and then placed on a stereotaxic instrument in a prone position. Activity of the phrenic nerve (PNA) was monitored at normocapnia and hypercapnia in hyperoxia. Microinjection of AVP into the lateral region of the VLM resulted in a brief apnea followed by a significant decrease in PNA amplitude and a concomitant significant increase in blood pressure. The inhibition of PNA with AVP treatment could be partly attenuated by hypercapnia but not by phentolamine. Both inhibition of PNA and pressor response with AVP microinjection into the lateral VLM were totally abolished after pretreatment with AVP V1A receptor antagonist. These results suggest that a vasopressinergic pathway projects to the lateral VLM and modulates cardiopulmonary functions via AVP V1A receptors on neurons within the lateral VLM.
Cheng
Meng-Tzu
MT
Department of Life Science, National Taiwan Normal University, Taipei, Taiwan, Republic of China.
Chuang
Ching-Wen
CW
Lin
Jin-Tun
JT
Hwang
Ji-Chuu
JC
D000818:Animals; D001127:Arginine Vasopressin / Q000008:administration & dosage / Q000037:antagonists & inhibitors / Q000494:pharmacology / Q000502:physiology*; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D018698:Glutamic Acid / Q000494:pharmacology; D006321:Heart / Q000187:drug effects / Q000502:physiology*; D006935:Hypercapnia / Q000209:etiology / Q000503:physiopathology; D018496:Hyperoxia / Q000139:chemically induced; D008168:Lung / Q000187:drug effects / Q000502:physiology*; D008297:Male; D008526:Medulla Oblongata / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D008845:Microinjections; D009433:Neural Inhibition; D010791:Phrenic Nerve / Q000187:drug effects / Q000502:physiology / Q000503:physiopathology; D051381:Rats; D017208:Rats, Wistar; D017483:Receptors, Vasopressin / Q000502:physiology*; D012119:Respiration / Q000187:drug effects; D015656:Respiratory Mechanics / Q000187:drug effects
D017483:Receptors, Vasopressin; D001127:Arginine Vasopressin; D018698:Glutamic Acid