Rostral ventrolateral medullary but not medullary lateral tegmental field neurons mediate sympatho-sympathetic reflexes in cats.
This study was designed to build on past work from this laboratory by testing the hypothesis that medullary lateral tegmental field (LTF) neurons play a critical role in mediating sympathoexcitatory responses to activation of sympathetic afferent fibers. We studied the effects of microinjection of N-methyl-d-aspartate (NMDA) or non-NMDA receptor antagonists or muscimol bilaterally into the LTF on the area under the curve of the computer-averaged sympathoexcitatory potential in the right inferior cardiac nerve elicited by short trains of stimuli applied to afferent fibers in the left inferior cardiac or left splanchnic nerve (CN, SN) of baroreceptor-denervated and vagotomized cats anesthetized with a mixture of diallylbarbiturate and urethane. In contrast to our hypothesis, sympathoexcitatory responses to stimulation of CN (n = 5-7) or SN (n = 4-7) afferent fibers were not significantly affected by these procedures. We then determined whether the rostral and caudal ventrolateral medulla (RVLM, CVLM) and nucleus tractus solitarius (NTS) were involved in mediating these reflexes. Blockade of non-NMDA, but not NMDA, receptors in the RVLM significantly reduced the area under the curve of the sympathoexcitatory responses to electrical stimulation of either CN (P = 0.0110; n = 6) or SN (P = 0.0131; n = 5) afferent fibers. Neither blockade of excitatory amino acid receptors nor chemical inactivation of CVLM or NTS significantly affected the responses. These data show that activation of non-NMDA receptors in the RVLM is a critical step in mediating the sympatho-sympathetic reflex.
Barman
Susan M
SM
Dept. of Pharmacology and Toxicology, Michigan State Univ., East Lansing, MI 48824, USA. barman@msu.edu
Orer
Hakan S
HS
D000344:Afferent Pathways / Q000502:physiology; D000818:Animals; D001794:Blood Pressure; D002319:Cardiovascular System / Q000294:innervation*; D002346:Carotid Sinus / Q000294:innervation / Q000601:surgery; D002415:Cats; D004558:Electric Stimulation; D005071:Evoked Potentials; D018691:Excitatory Amino Acid Antagonists / Q000008:administration & dosage; D058785:GABA-A Receptor Agonists / Q000008:administration & dosage; D008297:Male; D008526:Medulla Oblongata / Q000187:drug effects / Q000502:physiology*; D008845:Microinjections; D011930:Reaction Time; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors; D012018:Reflex / Q000187:drug effects; D013153:Splanchnic Nerves / Q000502:physiology; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000502:physiology*; D013997:Time Factors; D014628:Vagotomy
D018691:Excitatory Amino Acid Antagonists; D058785:GABA-A Receptor Agonists; D016194:Receptors, N-Methyl-D-Aspartate
J Auton Nerv Syst. 1983 Aug;8(4):383-93
6668394
Am J Physiol. 1990 Sep;259(3 Pt 2):R549-60
2118732
Neurosci Lett. 2006 Dec 1;409(2):146-50
17014954
Brain Res. 1985 Feb 11;326(2):261-71
3971154
Gut. 2002 Jul;51 Suppl 1:i2-5
12077054
Annu Rev Neurosci. 2002;25:433-69
12052916
Am J Physiol. 1983 Aug;245(2):R241-50
6881383
Brain Res. 2002 Jan 18;925(1):55-66
11755900
Am J Physiol. 1993 Nov;265(5 Pt 2):R1006-13
8238600
Am J Physiol. 1997 Jun;272(6 Pt 2):H2843-51
9227564
J Hypertens. 2002 Sep;20(9):1675-88
12195099
Am J Physiol Regul Integr Comp Physiol. 2001 Sep;281(3):R935-43
11507011
Neurosci Lett. 2002 Jun 7;325(2):134-8
12044639
Am J Physiol Regul Integr Comp Physiol. 2000 Apr;278(4):R995-R1004
10749789
Am J Physiol Heart Circ Physiol. 2000 Nov;279(5):H2549-57
11045993
Am J Physiol Heart Circ Physiol. 2004 May;286(5):H1706-11
15072970
Physiol Rev. 1973 Oct;53(4):916-47
4355517
Am J Physiol. 1977 Jun;232(6):H657-65
879305
J Biol Rhythms. 2000 Oct;15(5):365-79
11039915
Brain Res. 2005 Jul 12;1049(2):249-53
15950953
J Neurophysiol. 1994 Jul;72(1):106-20
7964996
Clin Exp Pharmacol Physiol. 2007 Apr;34(4):350-5
17324149
Brain Res. 1989 May 15;487(1):1-8
2752278
Hypertension. 2002 Jan;39(1):63-8
11799080
Am J Physiol Heart Circ Physiol. 2006 Sep;291(3):H1309-18
16632546
Am J Physiol. 1988 Sep;255(3 Pt 1):G319-28
3421337
Am J Physiol Regul Integr Comp Physiol. 2002 Dec;283(6):R1335-45
12388466
Am J Physiol. 1981 Apr;240(4):H539-45
7223905
Brain Res. 1985 May 6;333(2):325-9
3995298
Nat Rev Neurosci. 2006 May;7(5):335-46
16760914
Am J Physiol. 1984 Sep;247(3 Pt 2):R552-9
6476151
Am J Physiol Regul Integr Comp Physiol. 2005 May;288(5):R1396-410
15604299
Am J Physiol Regul Integr Comp Physiol. 2005 Dec;289(6):R1693-702
16099822
Auton Neurosci. 2003 Jul 31;106(2):119-31
12878081
J Neurophysiol. 1987 May;57(5):1410-24
3585474
Annu Rev Physiol. 1999;61:143-67
10099685
J Neurophysiol. 1985 Jun;53(6):1551-66
2989448
Am J Physiol Regul Integr Comp Physiol. 2004 Mar;286(3):R451-64
14604845
Brain Res. 1984 Nov 12;321(2):267-77
6498518
Am J Physiol Heart Circ Physiol. 2009 Oct;297(4):H1478-86
19684188
Am J Physiol. 1999 Nov;277(5):R1462-75
10564220
Am J Physiol. 1991 Jun;260(6 Pt 2):H1918-28
1905492
Physiol Rev. 1994 Jan;74(1):95-138
8295936