Morphometric Study of Mesenteric and Renal Arteries in Spontaneously Hypertensive Rats

Nordborg, Claes; Ivarsson, H.; Johansson, Barbro; Stage, Lars

doi:10.1097/00004872-198312000-00002

Cited by 19 publications

(11 citation statements)

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“…[4][5][6][7][8]10,11,15,18 In our colony, conscious MAP was not different between SHRs and WKY rats at 4 weeks of age; however, structurally based vascular resistance properties were higher in both 2-and 4-week-old SHRs versus WKY rats. These findings extend our previous results in rats from the same colony and suggest that vascular resistance properties differ to the same extent (ie, Ϸ30%) from neonatal to adult SHRs (Յ50 weeks), whereas the full expression of hypertension in SHRs only appears at Ϸ14 weeks of age.…”

Section: Discussionmentioning

confidence: 58%

“…[1][2][3] Despite the number of studies describing vascular morphometric and histological differences in young SHRs, [4][5][6][7][8][9] evidence linking blood pressure elevations with vascular structural and functional changes remains unresolved in the neonatal and weaning SHRs. The hypothesis that vascular structural changes antecede and initiate a rise in arterial pressure has been disputed for 2 main reasons, the presence 8,10-13 or lack [4][5][6][7]9,14,15 of blood pressure elevation in studies of young SHRs and substantial differences between body weights of SHRs and Wistar-Kyoto (WKY) rats 4,15 or body weights not being reported.…”

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confidence: 99%

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Altered Vascular Resistance Properties and Acute Pressure-Natriuresis Mechanism in Neonatal and Weaning Spontaneously Hypertensive Rats

2012

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Abstract-Although it has been extensively scrutinized, the factor(s) involved in the initiation and development of hypertension in spontaneously hypertensive rats (SHRs) remains unresolved. The objective of the present study was to determine whether, early in development, the causal mechanism(s) for the development of hypertension in young SHRs involves an integration of 2 processes, specifically an upregulation of structurally based vascular resistance properties and a rightward shift in the hemodynamic component of pressure-natriuresis. Mean arterial pressure was determined in conscious 4-week-old SHRs and Wistar-Kyoto rats via previously implanted aortic catheters. Structurally based hindlimb vascular resistance properties were assessed in 2-and 4-week-old SHRs and Wistar-Kyoto rats. Renal interstitial hydrostatic pressure was measured after short-term manipulations of renal arterial pressure (RAP) in 4-week-old, anesthetized rats. Although mean arterial pressure in conscious SHRs (113Ϯ5 mmHg) and Wistar-Kyoto rats (110Ϯ6 mmHg) was not significantly different at 4 weeks of age, SHRs at 2 and 4 weeks of age already had increases in structurally based vascular resistance properties of Ϸ30% above age-and weight-matched Wistar-Kyoto rats. Furthermore, the acute RAP-renal interstitial hydrostatic pressure relationship was found to be linear in both strains, and the temporal coupling of the stimulus to response was rapid; that is, renal interstitial hydrostatic pressure responses to changes in RAP were Ͻ2 s. Although the slope of the RAP-renal interstitial hydrostatic pressure relationship was not significantly different between strains, the relationship was significantly shifted (18%) to higher RAPs in SHRs. These results suggest that alterations in both vascular structure and renal function in young SHRs occur before elevations in mean arterial pressure. A lthough the factors responsible for the initiation and development of genetic hypertension have been extensively studied in the spontaneously hypertensive rat (SHR), the basis and time course for blood pressure elevation remain enigmatic. Specifically, what remains controversial is whether the 2 most widely studied processes, vascular abnormalities and renal dysfunction, lead to increases in arterial pressure or vice versa.Since the 1970s, 1 it has been well established that vascular abnormalities, such as increases in vascular resistance, vascular reactivity to vasoconstrictors, and media:lumen ratio, are associated with hypertension in the adult SHR.1-3 Despite the number of studies describing vascular morphometric and histological differences in young SHRs, 4-9 evidence linking blood pressure elevations with vascular structural and functional changes remains unresolved in the neonatal and weaning SHRs. The hypothesis that vascular structural changes antecede and initiate a rise in arterial pressure has been disputed for 2 main reasons, the presence 8,10-13 or lack 4-7,9,14,15 of blood pressure elevation in studies of young SHRs and substantial differences be...

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Section: Discussionmentioning

confidence: 58%

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confidence: 99%

Altered Vascular Resistance Properties and Acute Pressure-Natriuresis Mechanism in Neonatal and Weaning Spontaneously Hypertensive Rats

2012

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“…10 There is evidence that the hypertensive structural modification may differ with the arterial bed studied. 24 To what extent the various calibre segments of the arterial tree are involved is debated. 10 Measurements at specified sites in the arterial tree allow a comparison of luminal and wall dimensions as separate factors, which is essential for the evaluation of the hemodynamic effects of an altered wall to lumen ratio.…”

Section: Discussionmentioning

confidence: 99%

The morphometry of consecutive segments in cerebral arteries of normotensive and spontaneously hypertensive rats.

Nordborg¹,

Fredriksson²,

Johansson³

1985

Stroke

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313SUMMARY The media cross-sectional area, the media thickness, the internal radius and the ratio between media thickness and internal radius were determined in consecutive sections of extraparenchymal cerebral arteries of 7-and 12-month-old normotensive and spontaneously hypertensive rats. The study included intracranial pial and basal arteries as well as extracranial cervical arteries. In the chronically hypertensive rats the media to radius ratio was consistently higher than in normotensive rats over the entire calibre spectrum investigated (radius 5-400 /im). The increase of the ratio in the extracranial arteries of the hypertensive rats was exclusively due to a thicker media. In the basal intracranial arteries the increase of ratio was due to a thicker media and/or a smaller internal radius in 7-and 12-month-old rats with moderate hypertension (mean arterial pressure, MAP 171 ± 8 and 177 ± 7 mm Hg respectively). In 7-month-old rats with severe hypertension (MAP 204 ± 1 1 mm Hg) the increase of ratio was mainly due to a smaller internal radius. The observed structural alterations are likely to be of hemodynamic importance. Stroke Vol 16, No 2, 1985 THE JAPANESE STRAIN of spontaneously hypertensive rats (SHR) 1 and its stroke-prone substrain (SHRSP) 2 are extensively used in experimental hypertension research. Hemodynamic studies indicate similarities to primary hypertension in man.3 Compared to normotensive rats the cerebrovascular resistance is enhanced. Thus, in most conscious SHRSP with markedly increased blood pressure the cerebral blood flow is not altered.4 SHR are also less prone to develop bloodbrain barrier dysfunction in response to an abrupt rise in blood pressure than normotensive rats, 5 " 8 i.e. the microvessels are better protected against overdistension.The heightened cerebrovascular resistance in SHR may be functional and/or structural. 9 To what extent the various calibre segments of the cerebral arterial tree are involved is debated.10 " Intravital studies on the main cortical surface branches of the middle cerebral artery, monitored through a closed cranial window by the aid of a multichannel videoangiometer, have demonstrated significantly smaller luminal diameters in SHR compared to normotensive Wistar Kyoto rats (WKY) at rest as well as during dilatation.12 This is in agreement with an earlier study indicating a higher resistance in the relaxed cerebrovascular bed in SHR than in WKY. 13In the smallest pial 14 "16 and intraparenchymal arteries 17 of SHR and SHRSP, morphometric measurements have shown increased media or wall thickness to radius ratios. Little is known about more proximal parts of the cerebral vasculature in SHR and SHRSP, although it has been reported that the diameters of the Received September 19, 1983; revision # 3 accepted October 10, 1984. arteries in the circle of Willis do not differ significantly from controls. 18 In the present study we investigated the entire calibre spectrum of the extraparenchymal cerebral arteries of WKY, SHR and SHRSP at standardiz...

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“…The histopathological resemblance between these experimentally induced vascular lesions and those observed in benign and malignant nephrosclerosis in human kidneys have long been documented. Medial thickening with narrowing of the lumen resulting from hypertrophy of smooth muscle cells (Nordborg et al, 1983;Hampton et al, 1989;Vial & Boyd 1989;Lee, 1987;Mulvany & Aalkjaar 1990;Owens & Schartz, 1982;Chobanian et al, 1984;Ross, 1993) is followed by segmental hyalinosis of the vessel wall of interlobular arteries and afferent arterioles. In humans studies using light microscopy and imunofluorescence these lesions were better characterized and termed "benign nephrosclerosis" (Valenzuela, 1980;Fisher,1966).…”

Section: Pathogenesis Of Hypertensive Renal Damagementioning

confidence: 99%

Hypertension and Chronic Kidney Disease: Cause and Consequence – Therapeutic Considerations

Morgado¹,

Neves²

2012

Antihypertensive Drugs

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Morphometric Study of Mesenteric and Renal Arteries in Spontaneously Hypertensive Rats

Cited by 19 publications

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Altered Vascular Resistance Properties and Acute Pressure-Natriuresis Mechanism in Neonatal and Weaning Spontaneously Hypertensive Rats

Altered Vascular Resistance Properties and Acute Pressure-Natriuresis Mechanism in Neonatal and Weaning Spontaneously Hypertensive Rats

The morphometry of consecutive segments in cerebral arteries of normotensive and spontaneously hypertensive rats.

Hypertension and Chronic Kidney Disease: Cause and Consequence – Therapeutic Considerations

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