• The Korean Journal of Physiology
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• 제25권2호
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• pp.201-209
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• 1991

The rostral ventrolateral medulla (RVLM) has been established recently as a sympathoexcitatory area. The present study was conducted to investigate whether the somatosympathetic pressor and/or depressor responses are mediated through RVLM in cats anesthetized with ${\alpha}-chloralose$. An occipital craniectomy was performed and ventrolateral medulla were stimulated either electrically or chemically to evoke changes in arterial blood pressure. And then the effect of lesions in the ventrolateral medulla on the changes in blood pressure elicited by the peripheral nerve stimulation was observed. Followings are the results obtained: 1) Pressor areas were found in the ventrolateral medulla, lateral reticular nucleus and rostral dorsal area. 2) Depressor areas were found mainly in the ventrolateral medulla rostral to the pressor areas. 3) Some areas showed biphasic responses: a depressor response to lower frequency and a pressor response to higher frequency stimulation. 4) After electrical lesion in pressor area in RVLM, the somatosympathetic pressor response was abolished or depressed markedly. The somatosympathetic depressor response, however, remained after the lesion. 5) Electrical lesion in the depressor area abolished somatosympathetic depressor response. From the above results it is concluded that somatosympathetic pressor response is mediated through RVLM, while somatosympathetic depressor response is not mediated through RVLM.

• 대한약리학회지
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• 제23권2호
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• pp.77-85
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• 1987

혈압과 심박수의 중추조절에 대한 복외측 연수의 choline성 수용체의 역할을 규명하기 위하여 본 연구를 실시하였다. urethane으로 마취한 흰쥐에서 신경흥분성 아미노산인 L-glutamate(300 ng/site)를 복외측 연수에 미세주사하여 승압부위 (VLPA)와 감압부위 (VLDA)를 각각 기능적으로 확인하였다. VLPA와 VLDA에 각각 여러가지 choline성 약물들과 choline성 수용체의 길항제들을 양측으로 미세주사하여 다음과 같은 결과를 관찰하였다. 1. VLPA에 ca.bachol(300 ng/site)를 미세주사한 후 현저한 혈압상승 및 빈맥이 일어났으며, 이 반응은 hexamethonium ($4\;{\mu}g/site$)의 전처치에 의하여 차단되지 않았다. 2. VLPA에 physostigmine (200 ng/site)과 oxot.emo.me (300 ng/site)을 미세주사한 후 각각 현저한 혈압상승이 일어났다. 3. VLPA에 atropine($4\;{\mu}g/site$)을 미세주사한 후 현저한 혈압하강 및 서맥이 일어났다. 4. VLDA에 acetylcholine(500 ng/site)과 dimethylphenylpipe.azinium (500 ng/site)을 미세주사한 후 각각 현저한 혈압하강 및 서맥이 일어났다. 5. VLDA에 acetylcholine(500 ng/site)을 미세주사한 후 유발된 혈압하강 및 서맥반응은 hexamethonium($4\;{\mu}g/site$) 전처치에 의하여 차단되었다. 이상의 결과로 보아 흰쥐의 복외측 연수의 승압부위에서는 muscarine성 수용체를 통하여 혈압상승 및 빈맥반응이 일어나고 감압부위에서는 nicotine성 수용체를 통하여 혈압하강 및 서맥 반응이 일어나는 것으로 사료된다.

• The Korean Journal of Physiology and Pharmacology
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• 제1권6호
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• pp.639-645
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• 1997

The purpose of the present study is to determine the role of muscarinic cholinergic receptors of posterior hypothalamus in the central blood pressure regulation when respiration is controlled. In anesthetized and artificially ventilated rats, vasodepressor response was evoked by injection of L-glutamate(10 nmol) neuroexcitatory amino acid into the posterior hypothalamic area. The injection of $carbachol(0.5{\sim}8\;nmol)$ into the same area induced dose-dependent vasodepressor and bradycardic responses. Pretreatment with atropine(4 nmol) completely blocked the vasodepressor response to carbachol(2 nmol). In contrast, in spontaneously breathing rats, the injection of carbachol(8 nmol) into the posterior hypothalamic area induced the vasopressor and tachycardic responses. These results suggest that the muscarinic cholinergic receptors in the posterior hypothalamic area primarily play an inhibitory role in the central regulation of blood pressure and heart rate.

• The Korean Journal of Physiology
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• 제27권2호
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• pp.185-197
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• 1993

The rostral ventrolateral medulla (RVLM) includes vasopressor neurons, which transmit activation signals to the intermediolateral nucleus (IML) of the spinal cord, where the preganglionic sympathetic nucleus is located, to raise arterial blood pressure (BP). However, controversy exists as to the possible depressor area in the RVLM and the pathway involved. The present study persued evidence far the location of depressor neurons and the pathway by simultaneously observing changes in BP and the firing rate (FR) of cardiovascular neurons (CVNs) in the RVLM during the somatosympathetic reflex (SSR) elicited by peripheral nerve stimulation, since CVNs are known to contribute to the generation of the sympathetic nerve discharge. In 42 cats, anaesthetized with $\alpha-chloralose$, single unit recording was performed, using carbon filament electrodes inserted into the RVLM, enabling estimation of the post R wave unit histogram (PR-UNlT) and the spike triggered average of sympathetic nerve discharge (STA-SND), allowing identification of CVNs. Antidromic stimulation of spinal $T_2$ segment was followed to determine whether the identified CVN projects axonal endings to the spinal cord (reticulospinal neuron). The sciatic nerve was electrically stimulated at $A\delta-intensity$ (1 mA, 0.1 ms), 1 Hz and C-intensity (10 mA, 0.5 ms), 20 Hz to elicit the depressor, and pressor responses of the SSR, respectively. Simultaneous measurement of CVN firing rate was made. Experimental results are summarized as follows. 1) 20 out of 98 CVNs had axonal projections to the spinal cord and 17 out of 98 CVNs showed FR changes during SSR. 2) Response patterns of FR and BP during SSR were classified into 8 types. 3) These 8 different response patterns could be further classified into those from pressor and depressor neurons. These results demonstrate that some CVNs were identifiable as reticulospinal neurons responding to anti-dromic stimulation and that CVNs operating as depressor neurons as well as pressor neurons exist in the RVLM, both of which are involved with SSR mediation. Therefore, evidence was found that an independent depressor pathway might be involved in the mediation of SSR.