Renal Vasodepressor Mechanism: Characterization by Chemical Medullectomy

Swales, J. D.; Bing, R. F.; Edmunds, Matthew R.; Russell, Ginny

doi:10.1097/00000441-198804000-00004

Cited by 10 publications

(7 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…During the past decades the renal medulla has been recognized as an important regulator of arterial blood pressure, mainly because of its capability to secrete depressor substances (Swales et al 1988, Muirhead 1990, Christy et al 1991. The most likely responsible depressor substance is the almost neutral lipid fraction, medullipin, extensively studied by Muirhead andcoworkers (1982, 1990).…”

mentioning

confidence: 99%

Effect of nitric oxide and renal nerves on renomedullary haemodynamics in SHR and Wistar rats, studied with laser Doppler technique

Bergström

Rudenstam

Taghipour

et al. 1996

Acta Physiologica Scandinavica

View full text Add to dashboard Cite

The threshold for activation of the humoral renal antihypertensive system, presumably residing in the renomedullary interstitial cells (RIC), is substantially reset upwards in the spontaneously hypertensive rat (SHR). Depressor reactions, normally elicited by an increased renal perfusion pressure, can be inhibited either by high frequency renal nerve stimulation or blockade of nitric oxide synthesis, i.e. manoeuvres decreasing renal blood flow at this high perfusion pressure. The present study was designed to explore the effects on regional renal haemodynamics of blocking NO synthesis with N-omega-nitro-L-arginine (L-NNA) in chloralose anaesthetized SHR and Wistar rats. Mean arterial blood pressure (MAP), heart rate (HR), renal blood flow (RBF), cortical blood perfusion (CBP) and papillary blood perfusion (PBP) were measured in renally innervated and denervated SHR (Si n = 8, Sd n = 8) and in Wistar rats (Wi n = 10, Wd n = 10). An innervated non-treated Wistar group served as control (Ci n = 12). The laser Doppler technique was used to record CBP and PBP. MAP increased in all groups receiving L-NNA while HR, RBF and CBP simultaneously decreased. The relative decreases in RBF were more marked into the two SHR groups than in the corresponding Wistar groups. After L-NNA PBP also decreased in all four groups despite the increased MAP and more so in the Si group; Wi -19 +/- 8 (P < 0.05), Wd -17 +/- 6 (P = 0.07), Si -50 +/- 9 (P < 0.01) and Sd -25 +/- 9% (P < 0.05). We conclude that NO is important for maintaining PBP especially in SHR. The more marked decrease in PBP in the innervated SHR suggests a NO/renal nerve interaction in the control of renomedullary blood flow in SHR. This finding may be of importance for the regulation of the humoral renal depressor mechanism.

show abstract

mentioning

confidence: 99%

Effect of nitric oxide and renal nerves on renomedullary haemodynamics in SHR and Wistar rats, studied with laser Doppler technique

Bergström

Rudenstam

Taghipour

et al. 1996

Acta Physiologica Scandinavica

View full text Add to dashboard Cite

show abstract

“…Such a medullectomy model has exclusively served to explore the possible role of medulla in blood pressure control, because interstitial cells of this portion are capable of producing an antihypertensive substance [8][9][10]. However, apart from offering such a unique experimental situation, BEA also brings about a renal tubulo-interstitial pathology that is quite identical with chronic TIN.…”

Section: Discussionmentioning

confidence: 99%

Long-Term Effects of Enalapril in Rat with Experimental Chronic Tubulo-interstitial Nephropathy

Uemasu¹,

Fujiwara²,

Munemura³

et al. 1993

Am J Nephrol

View full text Add to dashboard Cite

The aim of this study was to determine whether or not angiotensin-converting enzyme inhibitor, enalapril, could ameliorate the chronic tubulo-interstitial nephropathy (TIN) in uninephrectomized (UNx) rats. Chronic TIN(M) was induced by 2-bromoethylamine hydrobromide. Rats were assigned to five groups; control, UNx-control (UNxC), UNx treated with enalapril (UNxE), UNxMC and UNxME. Enalapril was given for 12 months as drinking water (50 mg/l). At 6 months, albuminuria in UNxE decreased significantly compared with UNxC, but without change in UNxM rats. By 12 months, although all rats in control, UNxC and UNxE remained alive, 1 and 4 rats died in UNxME and UNxMC, respectively. Albuminuria in UNxC was reduced significantly by enalapril but not in UNxM rats. Both urine volume and urine osmolality became equal to control by enalapril in UNx rats, but not in UNxM rats. Serum cholesterol levels were normalized by enalapril in UNx rats, but not in UNxM rats. Levels of serum creatinine and blood urea nitrogen were invariably higher in UNxM than in UNx rats, irrespective of enalapril. Glomerular sclerosis was statistically decreased by enalapril in both UNx and UNxM rats. Enalapril reduced the overall tubulo-interstitial lesions in UNx rats, but not in UNxM group. However, in UNxM rats tubular changes in medullary portion were significantly ameliorated by enalapril. These data suggest that enalapril has a beneficial effect on chronic TIN in this model.

show abstract

“…Because there is evidence that SAD promotes an increased sympathetic tone, 8 - 12 the lack of medullipin II may play a role in the increased MAP response to SAD by facilitating peripherally the sympathetic drive to resistance vessels. 3 In normal rats, medullectomy is initially associated with moderate arterial pressure elevation, 13 probably linked to a significant tachycardia and an increase in cardiac output.…”

Section: Discussionmentioning

confidence: 99%

Chemical renal medullectomy and arterial pressure response to sinoaortic denervation.

Beloni

Silva-Costa²,

Machado³

et al. 1992

Hypertension

View full text Add to dashboard Cite

We investigated in conscious Wistar-Kyoto rats the effect of chemical renal medullectomy on the responses of mean arterial pressure, arterial pressure lability, and heart rate to sinoaortic deafferentation (SAD). Chemical medullectomy was obtained by the intravenous administration of 2-bromoethylamine hydrobromide (2-BEA) 2 -3 weeks before SAD or sham SAD. Chemically medullectomized rats were compared with control rats treated with saline. In control rats, the increase in mean arterial pressure elicited by SAD was not significantly greater than that produced by sham SAD. In medullectomized rats, SAD significantly increased mean arterial pressure compared with sham SAD. No direct relation was observed between the response of mean arterial pressure to SAD and the grade (1, 2, or 3) of lesion of the renal papilla. In control rats, SAD increased significantly arterial pressure lability. Chemical medullectomy did not affect basal lability or the increased lability after SAD. No direct relation was observed between increased arterial pressure lability due to SAD and the grade of lesion of the renal papilla. SAD produced a conspicuous tachycardia in control rats. Chemical medullectomy did not affect basal heart rate or the tachycardia produced by SAD. No direct relation was observed between the extent of this tachycardia and the grade of lesion of the renal papilla. These data indicate that lesions of the renal papilla lead to a significant increase in mean arterial pressure after SAD, without affecting basal pressure or heart rate. In addition, SAD per se did not increase significantly the mean arterial pressure in control rats. In conclusion, chemical ablation of the renal medulla seems to render rats more sensitive to a hypertensive stimulus such as SAD, and the mechanism probably involves the lack of the suppressive effect of medullipin II on sympathetic activity. {Hypertension 1992;19[suppl II]:II-116-II-120)

show abstract

Renal Vasodepressor Mechanism: Characterization by Chemical Medullectomy

Cited by 10 publications

References 22 publications

Effect of nitric oxide and renal nerves on renomedullary haemodynamics in SHR and Wistar rats, studied with laser Doppler technique

Effect of nitric oxide and renal nerves on renomedullary haemodynamics in SHR and Wistar rats, studied with laser Doppler technique

Long-Term Effects of Enalapril in Rat with Experimental Chronic Tubulo-interstitial Nephropathy

Chemical renal medullectomy and arterial pressure response to sinoaortic denervation.

Contact Info

Product

Resources

About