| 1. |
- Holm, Lena, et al.
(författare)
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Resetting of the pressure range for blood flow autoregulation in the rat kidney.
- 1990
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Ingår i: Acta Physiologica Scandinavica. - 0001-6772 .- 1365-201X. ; 138:3, s. 395-401
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Tidskriftsartikel (refereegranskat)abstract
- Both a myogenic response and the tubuloglomerular feedback control mechanism seem to be involved in autoregulation of glomerular filtration rate (GFR) and renal blood flow (RBF). Earlier experiments have shown that clamping of renal arterial perfusion pressure, below the autoregulatory range, reduces single-nephron GFR, and that this low value is maintained during the first 10-15 min after release of the clamp. It was also found that the tubuloglomerular feedback mechanism in the early declamp phase was strongly activated to reduce GFR. These findings can not be easily understood with the current knowledge of autoregulation, but would suggest a resetting of RBF and GFR autoregulation to a new level. To test this, left renal arterial perfusion pressure was reduced from 100 to 60 mmHg during 20 min with and without angiotensin converting enzyme inhibition (0.5 mg i.v. enalapril). Renal blood flow was measured with laser-Doppler flowmetry. When arterial perfusion pressure was reduced from 100 to 60 mmHg for 20 min, RBF was reduced to 77% of control and remained at this low level during the first minutes of declamp. In this situation there was an autoregulation to a new level. Renal blood flow was then slowly normalized (16.1 min). In the enalapril-treated animals RBF was only reduced to 85% during the 20 min of clamping and returned immediately to the control level at declamp. Thus, these experiments demonstrate that if renal blood flow is decreased by reducing the perfusion pressure below the normal autoregulatory range the pressure range for blood flow autoregulation resets to a lower level and that this change is mediated via the renin-angiotensin system.
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| 2. |
- Holm, Lena, et al.
(författare)
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Stimulation of acid secretion increases the gastric gland luminal pressure in the rat.
- 1992
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Ingår i: Gastroenterology. - 0016-5085 .- 1528-0012. ; 103:6, s. 1797-803
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Tidskriftsartikel (refereegranskat)abstract
- The gastric mucosal gland luminal pressure was measured in vivo with a pressure-sensitive microelectrode technique (servo-null) in anesthetized rats. A microelectrode was inserted into a gland lumen by means of a micromanipulator at an angle of 30 degrees to the mucosal surface. Acid secretion was estimated by measuring the pH in the solution covering the mucosa. During control conditions, when the mucosa was secreting acid spontaneously, gland luminal pressure was 12.3 +/- 1.2 mm Hg. At about 9 minutes after starting pentagastrin administration, the luminal pressure stabilized at 17.2 +/- 1.7 mm Hg. In the rats given impromidine (500 micrograms.kg-1.h-1) luminal pressure gradually increased (during 9-10 minutes) from a control level of 9.0 +/- 1.9 to 17.3 +/- 2.6 mm Hg. During the majority of experiments, the luminal pressure oscillated at 3-7 cycles per minute. The results show that intraluminal pressure increases during stimulated acid secretion, indicating that a resistance to the volume secretion exists in the upper part of the gastric crypts. This hydrostatic pressure may well be the driving force for creating channels for acid and pepsin to cross the mucus layer covering the mucosal surface.
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| 3. |
- Morsing, P, et al.
(författare)
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Renal interstitial pressure and tubuloglomerular feedback control in rats during infusion of atrial natriuretic peptide (ANP).
- 1992
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Ingår i: Acta Physiologica Scandinavica. - 0001-6772 .- 1365-201X. ; 146:3, s. 393-8
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Tidskriftsartikel (refereegranskat)abstract
- Atrial natriuretic peptide (ANP), injected at physiological concentrations, is known to induce both natriuresis and diuresis. It has been suggested by some investigators that these changes result from an increasing glomerular filtration rate (GFR), but others have been unable to demonstrate an increased GFR. The tubuloglomerular feedback (TGF) mechanism is an important regulator of GFR, and the sensitivity of TGF is decreased during ANP administration. Furthermore, resetting of TGF is, in most instances, related to changes in renal interstitial hydrostatic and oncotic pressures. It is also known that ANP may increase capillary permeability which may change renal interstitial pressure. The present study was performed to examine renal interstitial pressures and the TGF mechanism during ANP infusion. In accordance with previous studies, TGF sensitivity was found to be decreased. The tubular flow rate which elicited half the maximal drop in stop-flow pressure (Psf) was increased from 18.5 to 25.7 nl min-1. In contrast, ANP infusion resulted in a decreased interstitial hydrostatic pressure and an increased interstitial oncotic pressure. From previous experiments, such changes in interstitial pressures would be expected to increase TGF sensitivity. The changes in interstitial pressure cannot, therefore, directly explain the resetting of the feedback mechanism. In conclusion, the present paper shows a decreased renal net interstitial pressure after intravenous administration of ANP.
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| 4. |
- Persson, Lena, 1951-, et al.
(författare)
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Nurse turnover with special reference to factors relating to nursing itself
- 1993
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Ingår i: Scandinavian Journal of Caring Sciences. - 0283-9318 .- 1471-6712. ; 7:1, s. 29-36
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Tidskriftsartikel (refereegranskat)abstract
- Nurse turnover may decrease the quality of nursing care due to the loss of knowledge. It also results in high costs for the employer. Hence, the factors contributing to nurse turnover, if correctly understood, are important in order to know how to reduce it. This study aimed at exploring what contributing factors nurses who had decided to leave referred to concerning their decision to resign. A questionnaire was posted to all nurses who had left within one county council and 142 nurses responded. The most important factors behind the decision to leave turned out to be the following: difficult to implement changes, lack of influence and recognition, to much weekend and evening duty as well as the psychological burden inherent in nursing. The importance of the first three factors became significantly more important when those who remained in the geographical area were compared with those who moved or started to study. The findings support the idea that job satisfaction indirectly influences nurses turnover. However, it also points to the fact that what increases job satisfaction in nursing may need further research. Psychological burden for instance has not been taken into consideration before. In order to increase job satisfaction, thereby reducing nurse turnover, influence and recognition, lessening of the psychological burden and individually planned work schedules seem to be the most important factors.
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