Autoregulation of renal blood flow: alteration by methoxyflurane.

Content Provider	Semantic Scholar
Author	Leighton, Katherine Koth, B. W. Wenkstern, B. M.
Copyright Year	1973
Abstract	THE FLOW OF BLOOD to the kidneys is apparently controlled by these organs themselves. Within certain limits this flow is independent of fluctuations in arterial pressure. 1 Thus renal blood flow tends to remain relatively constant in spite of the many fluctuations in pressure to which the systemic circulation is subject. That this regulation is indeed an autonomous function of the organ is shown by experiments involving isolated perfused kidneys wherein renal blood flow remains constant in the face of changing perfusion pressures. 2 The upper and lower limits of mean arterial pressure throughout which this autoregulation is maintained are variously described. Hatch and Johnson, in their review of intrarenal blood flow published in 1960, give the figures of 200 mm Hg and 70 mm Hg respectively, a The kidney is not paramount in the control of its blood flow. In severe haemorrhage, for example, with increased sympathetic nervous activity, renal flow may be appreciably reduced when mean arterial pressure remains above the lower critical level for normal autoregulation. 4 A similar fall in blood flow may be observed in conditions of acute hypoxia where, once again, autoregulatory mechanisms are superseded. ~ This latter response is neurogenic in origin since there is no decrease in blood flow in the presence of hypoxia if the carotid sinus is first denervated and the depressor nerves sectioned. 6 In the absence of such over-riding mechanisms, not only is renal blood flow subject to autoregulation but so also is glomerular filtration rate. 7 This latter observation suggested a preglomerular site for autoregulation and this appears to have been confirmed by experimental observation, s It should be noted that although it has generally been held that autoregulation of renal blood flow applies only to cortical perfusion 9 Grangsjo and Wolgast have presented convincing evidence recently for autoregulafion of medullary blood flow. 1° The significance of this is obvious. Although only some seven percent of the total blood flow to the kidney perfuses medullary tissue, this flow may profoundly affect interstitial osmolarity in the vicinity of the collecting systems of the nephron and this, in turn, influences the character of the final urinary product. Considerable debate has centred upon the mechanisms whereby the kidney ex-
Starting Page	96S
Ending Page	96S
Page Count	1
File Format	PDF HTM / HTML
Alternate Webpage(s)	https://rd.springer.com/content/pdf/10.1007/BF03027205.pdf
PubMed reference number	4689264v1
Volume Number	20
Issue Number	2
Journal	Canadian Anaesthetists' Society journal
Language	English
Access Restriction	Open
Subject Keyword	Glomerular Filtration Rate Hemorrhage Homeostasis Hypoxia Kidney Mercury Methoxyflurane Nasal sinus Nephrons Nerve Organ Osmolarity Renal Circulation Renal Tissue Scientific Publication Structure of carotid sinus hatching
Content Type	Text
Resource Type	Article