摘要:

A real-time automatic digital image-processing algorithm was developed for measuring microvascular dimensions. Using video microscopic images of the vasculature, the video images are digitized and analyzed using contrast enhancement, frame averaging, and pattern recognition, rather than edge detection. Performance of the algorithm was evaluated for second- and third-order vessels surrounded by the complex interfering features of in vivo skeletal muscle. Graded diameter changes and vasomotion were induced with pharmacological agents. Data obtained by auto-tracking agreed with data obtained by traditional manual methods of measurement. These findings indicate that a pattern recognition algorithm based on cross-correlation analysis provides a highly accurate method for real-time automatic tracking of microvessel diameters.

ISSN:1018-1172    

DOI:10.1159/000158938

出版商:S. Karger AG    

年代:1992

数据来源: Karger

摘要:

Red blood cells (RBCs) and lysate products (erythrolysate) are consistently observed in lymph draining inflammatory reactions and from tissues subjected to trauma or surgical procedures. We determined previously that erythrolysate modulates lymphatic pumping by altering the pressures over which the lymph pump is active. The purpose of this study was to test the hypothesis that oxyhemoglobin was the active material within erythrolysate. To quantitate lymphatic pumping, bovine lymphatics were suspended in an organ bath preparation with the vessels cannulated at both inflow and outflow ends. By raising the heights of the Krebs reservoir and the outflow catheters appropriately, a transmural pressure could be applied to the vessels. This procedure stimulated pumping activity. Erythrolysate was prepared from sheep RBCs by lysis in Tris buffer and a portion of this was purified by column chromatography using DEAE-Sephadex A-50. Both the purified hemoglobin (10–5M) and crude erythrolysate (the latter diluted appropriately in Krebs solution to contain 10–5 M hemoglobin) reduced lymphatic fluid pumping approximately 70% over a period of 2 h. To determine whether this activity was due to the heme or the protein portion of the molecule, we compared the activity of purified oxyhemoglobin with that of its oxidized methemoglobin derivative. This was achieved by conversion with potassium ferricyanide. Methemoglobin was inactive, suggesting that the heme portion was important for the lymphatic effect. Further confirmation of this observation was provided by experiments with myoglobin which was purified from sheep heart. Oxymyoglobin, which shares an identical heme but has a different protein component, inhibited lymphatic pumping, when tested on the bovine lymphatics. These data suggest that oxyhemoglobin is the component within erythrolysate that modulates lymphatic pumping and we speculate that its presence in lymph (and the presence of other heme-containing proteins) may impair the ability of lymphatic vessels to drain liquid and protein from the tissue spaces and facilitate edema format

ISSN:1018-1172    

DOI:10.1159/000158939

出版商:S. Karger AG    

年代:1992

数据来源: Karger

摘要:

Supersensitivity of vascular smooth muscle to catecholamines in aldosterone-salt hypertensive rats appears to reside beyond the α1-adrenoceptor. The objective of this study was to assess the norepinephrine-stimulated production of arachidonic acid metabolites by aorta from control-salt rats (CSR) and aldosterone-salt hypertensive rats (AHR) to determine whether these metabolites might contribute to the altered sensitivity. Norepinephrine increased in a time-dependent manner the production of 6-keto-prostaglandin F α1 (6-keto-PGF α1), thromboxane B2 (TXB2) and prostaglandin E2 (PGE2) by the aortae of CSR. Production was an α1-adrenoceptor-mediated event since it was inhibited greatly by prazosin but not by yohimbine. Basal values of the metabolites did not differ for 6-keto-PGF α1 and TXB2, but were higher in AHR compared with CSR for PGE2. The norepinephrine concentration-response curve for 6-keto-PGF α1 was shifted significantly to the right for the AHR group compared with CSR (EC50 = 2.30 + 0.55 and 0.29 ± 0.07 µM, respectively) indicating decreased production of norepinephrine-stimulated prostaglandin I2 in AHR. The norepinephrine-stimulated TXB2 concentration-response curves for AHR and CSR were similar. Indomethacin was an effective inhibitor of TXB2 and 6-keto-PGF 1α production in both. Norepinephrine-stimulated contraction was significantly affected by indomethacin in CSR but not in AHR. Whereas we observed an attenuation of a norepinephrine-stimulated vasodilatory substance in aortae of AHR compared with CSR, the effect of attenuation on vascular activity is presently

ISSN:1018-1172    

DOI:10.1159/000158940

出版商:S. Karger AG    

年代:1992

数据来源: Karger

摘要:

The persistent effects on blood pressure of the angiotensin II receptor antagonist losartan and the converting enzyme inhibitor captopril were compared in the young spontaneously hypertensive rat (SHR). Losartan (DuP753/MK954, 15 mg/kg/day) and captopril (100 mg/kg/day) were given in the drinking water of 3-week-old SHRs for 4- and 10-week durations. Blood pressure was measured during treatment and after treatment was stopped until the age of 30 weeks. Both losartan and captopril given for 4 and 10 weeks prevented the development of hypertension during treatment and redevelopment of hypertension after treatment was stopped. Treatment for 10 weeks was more effective than for 4 weeks in lowering long-term pressure. Four weeks of treatment did not affect the mesenteric resistance artery media/lumen (m1/l1) ratio. In contrast, both losartan and captopril given for 10 weeks resulted in large and significant reductions in m1/l1 [5.3 ± 0.8 and 5.63 ± 0.8 vs 7.7 ± 0.8 × 10-2 (SD), p < 0.001]. In losartan-treated rats, plasma renin and angiotensin II concentration were increased between 4- and 7-fold at the end of both treatment periods. These findings show losartan to be an effective antihypertensive agent and support data implicating angiotensin II in the early events leading to hypertension in this model. The abilities of losartan and captopril to affect blood pressure without affecting vascular structure suggest that the latter is a poor predictor of long-term hypertensive levels in the

ISSN:1018-1172    

DOI:10.1159/000158941

出版商:S. Karger AG    

年代:1992

数据来源: Karger

摘要:

We studied the role of endothelium and eicosanoids in rhythmic contractions of rat thoracic aorta. Spontaneous oscillations were observed in 35% of 385 endothelium-intact and in 46% of 22 endothelium-denuded aortic strips from normotensive Sprague-Dawley male rats. Vasoactive agents (norepinephrine, epinephrine, phenylephrine, isoproterenol, arachidonic acid, PGF2α, serotonin, potassium, endothelin, atrial natriuretic factor and angiotensin II) induced rhythmic contractions in the majority of tissues. Rhythmic activity was also observed in aortic strips from adult female, pregnant and old male rats. Aortic oscillations were partially inhibited by indomethacin, ibuprofen and nordihydroguaiaretic acid (NDGA), and completely inhibited by indomethacin plus NDGA, nifedipine, low external calcium &(< 1 mM) and pre-treatment with dexamethasone. Indomethacin, NDGA and arachidonic acid did not affect oscillations of the portal vein. Rhythmic contractions were observed in thoracic aortic strips from neonatal but not from adult rabbits. However, oscillations could be induced in strips of the mesenteric artery and terminal abdominal aorta of adult rabbits. Also, adult rabbit thoracic aortic strips exhibited oscillations when set up in close proximity of rat aorta. It is suggested that rhythmic contractions are physiological characteristics of many and perhaps all blood vessels and may play a role in blood flow and turbulence; the likely cause of these oscillations is the cyclic release of one or more eicosanoids

ISSN:1018-1172    

DOI:10.1159/000158942

出版商:S. Karger AG    

年代:1992

数据来源: Karger

摘要:

Platelet homogenates from 200 ml blood of essential hypertensives (n = 28) and normotensives (n = 13) were deproteinized and separated by gel chromatography. The fractions obtained were then tested for vasopressor activity in the isolated perfused rat kidney. In both normotensives and hypertensives, two vasopressor fractions appeared. There was no difference in vasopressor activity in the first vasoactive fraction between normotensives and hypertensives. In the second vasoactive fraction, the hypertensive patients showed a significant higher activity than the normotensive subjects (increase in perfusion pressure by 35.9 ± 11.5 vs. 6.8 ± 5.3 mm Hg, p < 0.01). This vasopressor fraction was not inhibited by saralasin, phentolamine, ketanserin, nitroprusside and daltroban and was effective after pretreatment with indomethacin and reserpine and in enzymatically deendothelialized kidneys. The effect was reduced by nifedipine and unchanged by heating the fraction at 100°C and by incubation with proteinase K. It is concluded that a yet unidentified platelet-derived vasopressor agent may contribute to the enhanced vasoconstriction in essential hypertensi

ISSN:1018-1172    

DOI:10.1159/000158943

出版商:S. Karger AG    

年代:1992

数据来源: Karger

ISSN:1018-1172    

DOI:10.1159/000158944

出版商:S. Karger AG    

年代:1992

数据来源: Karger