The effects of stimulation of the left atrial receptors on sympathetic efferent nerve activity

Karim, Fazlul; Kidd, C.; Malpus, C. M.; Penna, P. E.

doi:10.1113/jphysiol.1972.sp010030

Cited by 215 publications

(141 citation statements)

References 40 publications

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“…Unloading of cardiac lowpressure baroreceptors preferentially activates renal sympathetic nerve activity with little effect on abdominal or peripheral sympathetic outflows. 29 In support of this contention, we have found that short-term enalaprilat administration to healthy subjects causes a slight reduction in mean arterial pressure, whereas left ventricular filling pressure is markedly reduced (M. Johansson et al, unpublished data, 1999).…”

Section: Discussionsupporting

confidence: 48%

Differentiated Response of the Sympathetic Nervous System to Angiotensin-Converting Enzyme Inhibition in Hypertension

et al. 2000

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Abstract-Hypertension with renal artery stenosis is associated with both an activated renin-angiotensin system and elevated sympathetic activity. Therefore, in this condition it may be favorable to use a therapeutic modality that does not reflexly increase heart rate, renin secretion, and sympathetic nervous activity. The purpose of the present study was to assess overall, renal, and muscle sympathetic activity after short-term administration of an angiotensin-converting enzyme inhibitor (enalaprilat) and a nonspecific vasodilator (dihydralazine) to hypertensive patients with renal artery stenosis. Forty-eight patients undergoing a clinical investigation for renovascular hypertension were included in the study. An isotope dilution technique for assessing norepinephrine spillover was used to estimate overall and bilateral renal sympathetic nerve activity. In 11 patients simultaneous intraneural recordings of efferent muscle sympathetic nerve activity were performed. Thirty minutes after dihydralazine administration, mean arterial pressure fell by 15%, whereas plasma angiotensin II, muscle sympathetic nerve activity, heart rate, and total body norepinephrine spillover increased (PϽ0.05 for all). In contrast, after enalaprilat administration a fall in arterial pressure similar to that for dihydralazine was followed by decreased angiotensin II levels and unchanged muscle sympathetic nerve activity, heart rate, and total body norepinephrine spillover, whereas renal norepinephrine spillover increased by 44% (PϽ0.05). Acute blood pressure reduction by an angiotensin-converting enzyme inhibitor provokes a differentiated sympathetic response in patients with hypertension and renal artery stenosis, inasmuch that overall and muscle sympathetic reflex activation are blunted, whereas the reflex renal sympathetic response to blood pressure reduction is preserved. (Hypertension. 2000;36:543-548.)Key Words: hypertension, renovascular Ⅲ sympathetic nervous system Ⅲ renin-angiotensin system R enovascular hypertension is a condition associated with both an activated renin-angiotensin system and elevated sympathetic nerve activity. 1,2 Previous data, obtained in experimental models, indicate a positive interaction between the renin-angiotensin and the sympathetic nervous systems. 3 Therefore, in renovascular hypertension it may be favorable to use a therapeutic modality that does not reflexly further increase heart rate, renin secretion, and sympathetic nervous activity. It is well known that certain drugs used in cardiovascular medicine affect various indices of sympathetic activity. For example, sympathetic activity increases in response to nonspecific vasodilators, whereas therapy with angiotensin-converting enzyme (ACE) inhibitors has demonstrated reduced peroneal sympathetic activity. 4 Thus, it appears that vasodilators and ACE inhibitors produce different sympathetic nerve responses; the effects of the latter could be due to either a direct-acting central mechanism 5,6 or a reduction of angiotensin II (Ang II) facilitatory e...

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Section: Discussionsupporting

confidence: 48%

Differentiated Response of the Sympathetic Nervous System to Angiotensin-Converting Enzyme Inhibition in Hypertension

et al. 2000

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“…However, in our reflex studies with intact kidneys, initial carotid sinus pressure was set to high, medium or low levels within the baroreceptor sensitivity range (Karim et al 1984(Karim et al , 1987(Karim et al , 1989bKarim & AlObaidi, 1990;Karim & Majid, 1990) and thus the reflex alteration of the renal nerve activity commenced from some basal on-going activity (Kendrick, Oberg & Wennergren, 1972;Linden, Mary & Weatherill, 1981). Although few studies have measure renal nerve activity in response to changes in carotid baroreceptor and chemoreceptor activities (Kezdi & Geller, 1968;Karim, Kidd, Malpus & Penna, 1972;Linden et al 1981), one has attempted to correlate sinus pressure (baroreceptor activity) with renal nerve activity and haemodynamics in the anaesthetized cat (Kendrick et al 1972). However, these workers have shown that even small changes in carotid sinus pressure can produce large changes in renal nerve activity.…”

Section: Discussionmentioning

confidence: 99%

The renal response to electrical stimulation of renal efferent sympathetic nerves in the anaesthetized greyhound.

Poucher

Karim

1991

The Journal of Physiology

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SUMMARY1. The effect of direct electrical stimulation of the renal efferent nerves upon renal haemodynamics and function was studied in greyhounds anaesthetized with chloralose and artificially ventilated. The left kidney was neurally and vascularly isolated, and perfused with blood from one of the femoral arteries at a constant pressure of 99+1 mmHg. Renal blood flow was measured with a cannulating electromagnetic flow probe placed in the perfusion circuit, glomerular filtration rate by creatinine clearance, urinary sodium excretion by flame photomnetry and solute excretion by osmometry. /J-Adrenergic receptor activation was blocked by the infusion of dl-propranolol (17 jug kg-' min-'). The peripheral ends of the ligated renal nerves were stimulated at 0 5, 1D0, 1-5 and 2-0 Hz.2. At 05 Hz frequency only osmolar excretion was significantly reduced (103+3-2%, P <005, n = 6). Reductions in sodium excretion (5336+85%, P < 0-01, n = 6) and water excretion (26-9 + 8 0 %, P < 0 05, n = 6) and further reductions of osmolar excretion (20 7+3-7%, P <001, n = 6) were observed at 10 Hz; however, these were observed in the absence of significant changes in renal blood flow and glomerular filtration rate. Significant reductions were observed in glomerular filtration rate at 15 Hz (163+41 %, P < 002, n = 5) and in renal blood flow at 2 0 Hz ( 1341 + 4 0 %, P < 0 05, n = 5). Further reductions in urine flow and sodium excretion were also observed at these higher frequencies.3. These results clearly show that significant changes in renal tubular function can occur in the absence of changes in renal blood flow and glomerular filtration rate when the renal nerves are stimulated electrically from a zero baseline activity up to a frequency of 15 Hz. Higher frequencies caused significant changes in both renal haemodynamics and function.

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“…Similarly, reflex effects from cardiopulmonary receptors are unlikely to be important since atrial distension (i.e. increased central blood volume) decreases MSA 54 in humans (Saito, Mano, Iwase, Koga & Matsukawa, 1987) but increases sympathetic activity to the heart in cats (Kollai, Koizumi, Yamashita & Brooks, 1970b;Karim, Kidd, Malpus & Penna, 1972).…”

Section: Sympathetic Activity At Restmentioning

confidence: 99%

Simultaneous measurements of cardiac noradrenaline spillover and sympathetic outflow to skeletal muscle in humans.

Wallin

Esler

Dorward

et al. 1992

The Journal of Physiology

274

193

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SUMMARY1. Muscle sympathetic nerve activity (MSA) was recorded in the peroneal nerve at the knee by microneurography in ten healthy subjects and determinations were made simultaneously of intra-arterial blood pressure, and whole-body and cardiac noradrenaline spillover to plasma. Measurements were made at rest, during isometric handgrip at 30% of maximum power and during stress induced by forced mental arithmetic.2. At rest there were significant positive correlations between spontaneous MSA (expressed as number of sympathetic bursts min-) and both spillover of noradrenaline from the heart and concentration of noradrenaline in coronary sinus venous plasma.3. Both isometric handgrip and mental arithmetic led to sustained increases of blood pressure, heart rate and MSA. Plasma concentrations of noradrenaline and spillover of noradrenaline (total body and cardiac) increased. In general the effects were more pronounced during handgrip than during stress. 4. When comparing effects during handgrip and stress the ratio between the fractional increases of MSA and cardiac noradrenaline spillover were significantly greater during handgrip.5. The data suggest (a) that there are proportional interindividual differences in the strength of resting sympathetic activity to heart and skeletal muscle which are determined by a common mechanism and (b) that handgrip and mental stress are associated with differences in balance between sympathetic outflows to heart and skeletal muscle.

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The effects of stimulation of the left atrial receptors on sympathetic efferent nerve activity

Cited by 215 publications

References 40 publications

Differentiated Response of the Sympathetic Nervous System to Angiotensin-Converting Enzyme Inhibition in Hypertension

Differentiated Response of the Sympathetic Nervous System to Angiotensin-Converting Enzyme Inhibition in Hypertension

The renal response to electrical stimulation of renal efferent sympathetic nerves in the anaesthetized greyhound.

Simultaneous measurements of cardiac noradrenaline spillover and sympathetic outflow to skeletal muscle in humans.

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