Biomaterial Database

Cardiovascular effects of lesions of the rostral ventrolateral medulla and the nucleus reticularis parvocellularis in rats. 1993

K L Cochrane, and M A Nathan

Department of Pharmacology, University of Texas Health Science Center, San Antonio.

This study explored the possibility that the nucleus reticularis parvocellularis (NRP) acts in concert with the rostral ventrolateral medulla (RVLM) in the maintenance of mean arterial pressure (MAP). Bilateral electrolytic or chemical lesions (kainic acid) were placed in three groups of rats anesthetized with sodium pentobarbital. In the different groups, lesions were placed only in the NRP or RVLM or in both the NRP and RVLM (NRPRVLM). Captopril (5 mg/kg, i.v.) and an arginine vasopressin antagonist (AVPX), d-pentamethylene methylated tyrosine (30 micrograms/kg, i.v.), were sequentially administered. A final procedure consisted of spinal cord transection. The RVLM lesions did not significantly alter MAP (before: 116 +/- 3 mmHg; after: 106 +/- 5 mmHg). Sequential administration of captopril and AVPX each reduced MAP to 87 +/- 5 mmHg and 62 +/- 4 mmHg, respectively. Spinal-cord transection lowered MAP to 38 +/- 2 mmHg. Lesions of the NRP also did not alter MAP (before: 113 +/- 4 mmHg; after: 118 +/- 5 mmHg). Captopril reduced MAP to 109 +/- 7 mmHg, AVPX had no effect, and spinal-cord transection decreased MAP to 31 +/- 3 mmHg. In contrast to the lack of effect of lesions of the RVLM or NRP on MAP, profound hypotension was observed after NRPRVLM lesions (before: 113 +/- 3 mmHg; after: 51 +/- 3 mmHg). Subsequent administration of captopril decreased MAP to 39 +/- 2 mmHg, and AVPX lowered MAP to 32 +/- 1 mmHg. Spinal-cord transection reduced MAP to 23 +/- 1 mmHg. Several conclusions can be drawn from this study. First, lesions of the RVLM do not decrease MAP because of compensation by the renin-angiotensin system and AVP secretion which is mediated by the NRP. Second, lesions of the NRP do not affect MAP because the intact RVLM can maintain sympathetic tone. Third, the profound hypotension observed after NRPRLVM lesions occurred because of the simultaneous impairment of sympathetic vasomotor activity and the neuroendocrine vasoconstrictor effects of the renin-angiotensin system and AVP secretion.

UI	MeSH Term	Description	Entries
D007022	Hypotension	Abnormally low BLOOD PRESSURE that can result in inadequate blood flow to the brain and other vital organs. Common symptom is DIZZINESS but greater negative impacts on the body occur when there is prolonged depravation of oxygen and nutrients.	Blood Pressure, Low,Hypotension, Vascular,Low Blood Pressure,Vascular Hypotension
D008297	Male		Males
D008526	Medulla Oblongata	The lower portion of the BRAIN STEM. It is inferior to the PONS and anterior to the CEREBELLUM. Medulla oblongata serves as a relay station between the brain and the spinal cord, and contains centers for regulating respiratory, vasomotor, cardiac, and reflex activities.	Accessory Cuneate Nucleus,Ambiguous Nucleus,Arcuate Nucleus of the Medulla,Arcuate Nucleus-1,External Cuneate Nucleus,Lateral Cuneate Nucleus,Nucleus Ambiguus,Ambiguus, Nucleus,Arcuate Nucleus 1,Arcuate Nucleus-1s,Cuneate Nucleus, Accessory,Cuneate Nucleus, External,Cuneate Nucleus, Lateral,Medulla Oblongatas,Nucleus, Accessory Cuneate,Nucleus, Ambiguous,Nucleus, External Cuneate,Nucleus, Lateral Cuneate
D009434	Neural Pathways	Neural tracts connecting one part of the nervous system with another.	Neural Interconnections,Interconnection, Neural,Interconnections, Neural,Neural Interconnection,Neural Pathway,Pathway, Neural,Pathways, Neural
D010424	Pentobarbital	A short-acting barbiturate that is effective as a sedative and hypnotic (but not as an anti-anxiety) agent and is usually given orally. It is prescribed more frequently for sleep induction than for sedation but, like similar agents, may lose its effectiveness by the second week of continued administration. (From AMA Drug Evaluations Annual, 1994, p236)	Mebubarbital,Mebumal,Diabutal,Etaminal,Ethaminal,Nembutal,Pentobarbital Sodium,Pentobarbital, Monosodium Salt,Pentobarbitone,Sagatal,Monosodium Salt Pentobarbital
D012084	Renin-Angiotensin System	A BLOOD PRESSURE regulating system of interacting components that include RENIN; ANGIOTENSINOGEN; ANGIOTENSIN CONVERTING ENZYME; ANGIOTENSIN I; ANGIOTENSIN II; and angiotensinase. Renin, an enzyme produced in the kidney, acts on angiotensinogen, an alpha-2 globulin produced by the liver, forming ANGIOTENSIN I. Angiotensin-converting enzyme, contained in the lung, acts on angiotensin I in the plasma converting it to ANGIOTENSIN II, an extremely powerful vasoconstrictor. Angiotensin II causes contraction of the arteriolar and renal VASCULAR SMOOTH MUSCLE, leading to retention of salt and water in the KIDNEY and increased arterial blood pressure. In addition, angiotensin II stimulates the release of ALDOSTERONE from the ADRENAL CORTEX, which in turn also increases salt and water retention in the kidney. Angiotensin-converting enzyme also breaks down BRADYKININ, a powerful vasodilator and component of the KALLIKREIN-KININ SYSTEM.	Renin-Angiotensin-Aldosterone System,Renin Angiotensin Aldosterone System,Renin Angiotensin System,System, Renin-Angiotensin,System, Renin-Angiotensin-Aldosterone
D012154	Reticular Formation	A region extending from the PONS & MEDULLA OBLONGATA through the MESENCEPHALON, characterized by a diversity of neurons of various sizes and shapes, arranged in different aggregations and enmeshed in a complicated fiber network.	Formation, Reticular,Formations, Reticular,Reticular Formations
D001794	Blood Pressure	PRESSURE of the BLOOD on the ARTERIES and other BLOOD VESSELS.	Systolic Pressure,Diastolic Pressure,Pulse Pressure,Pressure, Blood,Pressure, Diastolic,Pressure, Pulse,Pressure, Systolic,Pressures, Systolic
D002216	Captopril	A potent and specific inhibitor of PEPTIDYL-DIPEPTIDASE A. It blocks the conversion of ANGIOTENSIN I to ANGIOTENSIN II, a vasoconstrictor and important regulator of arterial blood pressure. Captopril acts to suppress the RENIN-ANGIOTENSIN SYSTEM and inhibits pressure responses to exogenous angiotensin.	(S)-1-(3-Mercapto-2-methyl-1-oxopropyl)-L-proline,Capoten,Lopirin,SQ-14,225,SQ-14,534,SQ-14225,SQ-14534,SQ 14,225,SQ 14,534,SQ 14225,SQ 14534,SQ14,225,SQ14,534,SQ14225,SQ14534
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia