Commissural nucleus of the solitary tract is important for cardiovascular responses to caudal pressor area activation.
The nucleus of the solitary tract (NTS) is the site of the first synapse of cardiovascular afferent fibers in the central nervous system. Important mechanisms for cardiovascular regulation are also present in the caudal pressor area (CPA) localized at the caudal end of the ventrolateral medulla. In the present study we sought to investigate the role of the commissural subnucleus of the NTS (commNTS) on pressor and tachycardic responses induced by l-glutamate injected into the CPA. Male Holtzman rats (n=8 rats/group) anesthetized with urethane (1.2 g/kg of body weight, iv) received injections of the GABA(A) receptor agonist muscimol into the commNTS. Unilateral injection of L-glutamate (10 nmol/100 nL) into the CPA increased mean arterial pressure (MAP, 31+/-4 mm Hg, vs. saline: 3+/-2 mm Hg) and heart rate (HR, 44+/-8 bpm, vs. saline: 10 +/-7 bpm). Inhibition of commNTS neurons with muscimol (120 pmol/60 nL) abolished the increase in MAP (9+/-4 mm Hg) and HR (17+/-7 bpm) produced by l-glutamate into the CPA. The present results suggest that the pressor and tachycardic responses to CPA activation are dependent on commNTS mechanisms.
Carolina Takakura
Ana
A
Department of Physiology, Universidade Federal de São Paulo-Escola Paulista de Medicina, 04023-060, São Paulo, SP, Brazil.
Santos Moreira
Thiago
T
Menani
José V
JV
Ribeiro Campos
Ruy
R
Colombari
Eduardo
E
D000704:Analysis of Variance; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology*; D007839:Functional Laterality; D018755:GABA Agonists / Q000494:pharmacology; D018698:Glutamic Acid / Q000494:pharmacology; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology*; D008297:Male; D008526:Medulla Oblongata / Q000033:anatomy & histology / Q000187:drug effects / Q000502:physiology*; D008845:Microinjections / Q000379:methods; D009118:Muscimol / Q000494:pharmacology; D011311:Pressoreceptors / Q000502:physiology*; D051381:Rats; D017552:Solitary Nucleus / Q000187:drug effects / Q000502:physiology*; D013997:Time Factors
D018755:GABA Agonists; D009118:Muscimol; D018698:Glutamic Acid