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At least 991 records · Page 55Linked to original sources
PubMed2002

Optimizing treatment of choroidal neovascularization feeder vessels associated with age-related macular degeneration.

PURPOSE: To optimize the method of treating choroidal neovascularization (CNV) associated with age-related macular degeneration (AMD). DESIGN: Experimental study and interventional case series. METHODS: The parameters associated with locating and then photocoagulating CNV feeder vessels were identified and optimized using published data and data derived from modeling the choroidal vasculature. Based on these optimized parameters, a prototype diagnostic/treatment system was designed that captures high-speed indocyanine green (ICG) angiogram images and facilitates analysis of the images by enhancing visualization of dye movement through CNV feeder vessels (FVs). The system also permits precise aiming and delivery of 810- nm wavelength photocoagulation laser energy to target FVs on a real-time ICG angiogram image of the choroidal vasculature. Target FVs are tracked by a joy-stick controlled laser aiming beam until an intravenously-injected high-concentration ICG dye bolus is observed to enter the target vessel, at which time the laser is fired. Proof of principle of the combined diagnosis/treatment system design for performing dye-enhanced photocoagulation (DEP) in the clinical setting and determination of the minimum DEP laser energy needed to close CNV FVs was made in 11 AMD patients requiring treatment of CNV, but for whom other treatment was not appropriate. RESULTS: Using ICG-DEP, CNV feeder vessels were closed with single pulse laser energy, delivering as little as 0.6 to 1.8 J of energy to the fundus, producing no visible change in the fundus. Successful FV closure was usually indicated immediately by presence of incarcerated ICG dye in the vessel adjacent to the burn site. The prototype system proved relatively easy to operate. After acquiring and interpreting diagnostic angiograms and repositioning a patient in front of the device, feeder vessel DEP and treatment evaluation required 15 to 20 minutes. CONCLUSIONS: Indocyanine green dye-enhanced photocoagulation of CNV feeder vessels, facilitated by use of a device that permits real-time visualization of the choroidal circulation while aiming the treatment laser beam, appears to minimize the amount of energy applied to the fundus and the volume of fundus tissue affected by treatment, compared with other treatment modalities. The combination diagnosis/treatment device should be useful in optimizing FV treatment and in refining and evaluating the efficacy of DEP in future clinical trials.

Aged↗
PubMed2002

Abnormalities in pericytes on blood vessels and endothelial sprouts in tumors.

Endothelial cells of tumor vessels have well-documented alterations, but it is less clear whether pericytes on these vessels are abnormal or even absent. Here we report that alpha-smooth muscle actin (alpha-SMA) and desmin-immunoreactive pericytes were present on >97% of blood vessels viewed by confocal microscopy in 100-microm-thick sections of three different spontaneous or implanted tumors in mice. However, the cells had multiple abnormalities. Unlike pericytes on capillaries in normal pancreatic islets, which had desmin but not alpha-SMA immunoreactivity, pericytes on capillary-size vessels in insulinomas in RIP-Tag2 transgenic mice expressed both desmin and alpha-SMA. Furthermore, pericytes in RIP-Tag2 tumors, as well as those in MCa-IV breast carcinomas and Lewis lung carcinomas, had an abnormally loose association with endothelial cells and extended cytoplasmic processes deep into the tumor tissue. alpha-SMA-positive pericytes also covered 73% of endothelial sprouts in RIP-Tag2 tumors and 92% of sprouts in the other tumors. Indeed, pericyte sleeves were significantly longer than the CD31-immunoreactive endothelial cell sprouts themselves in all three types of tumors. All three tumors also contained alpha-SMA-positive myofibroblasts that resembled pericytes but were not associated with blood vessels. We conclude that pericytes are present on most tumor vessels but have multiple abnormalities, including altered expression of marker proteins. In contrast to some previous studies, the almost ubiquitous presence of pericytes on tumor vessels found in the present study may be attributed to our use of both desmin and alpha-SMA as markers and 100-microm-thick tissue sections. The association of pericytes with endothelial sprouts raises the possibility of an involvement in sprout growth or retraction in tumors.

Actins↗
PubMed1998

Concomitant occlusive disease of the coronary arteries and great vessels.

BACKGROUND: Although an increasing number of elderly and high-risk patients, including those with generalized atherosclerosis, are undergoing coronary revascularization, few reports exist regarding the management of patients who have both occlusive disease of the great vessels and coronary artery disease. METHODS: Between 1972 and 1996, 31 consecutive patients (mean age, 56.5 years; 74% men) with multivessel coronary artery disease and symptomatic occlusive disease of the great vessels (25 single-vessel, 80.6%; 6 multiple-vessel, 19.4%) had 40 great vessels reconstructed by transthoracic bypass (n = 17, 42.5%), transthoracic endarterectomy (n = 8, 20%), or extrathoracic bypass (n = 15, 37.5%). All patients had simultaneous coronary artery bypass grafting (mean, 2.6 grafts per patient), and 8 patients had 10 distal carotid bifurcation endarterectomies (6 staged, 4 simultaneous). RESULTS: The early primary patency rate was 100%, and symptoms resolved completely in all 31 patients. There was 1 in-hospital death (3.2%) in a patient who had a respiratory arrest 11 days after operation. Perioperative morbidity included two myocardial infarctions (6.5%) and one opposite-hemisphere, embolic stroke (3.2%). Long-term follow-up of the 30 survivors (167.4 patient-years; mean, 5.6 years per patient) documented 5- and 10-year actuarial survival rates of 88.6% and 60.4%, respectively, with a 100% late brachiocephalic primary patency rate. Ten-year actuarial rates of freedom from the following events were as follows: death, 60.4%; myocardial infarction, 82.5%; stroke, 90.9%; percutaneous transluminal coronary angioplasty or redo coronary artery bypass grafting, 95.2%; and vascular operation or amputation, 78.4%. CONCLUSIONS: Depending on the anatomic distribution of the disease, an integrated approach to great vessel reconstruction that incorporated transthoracic and extrathoracic approaches and techniques of endarterectomy and bypass resulted in few adverse outcomes and excellent long-term patency. Simultaneous revascularization of the great vessels and coronary arteries can produce immediate and long-term, symptom-free outcome with acceptably low operative risk.

Aged↗
PubMedDate not supplied

Measurement of blood flow velocity in feeder vessels of choroidal neovascularization by a scanning laser ophthalmoscope and image analysis system.

PURPOSE: To measure the blood flow velocities in feeder vessels of patients with choroidal neovascularization (CNV) secondary to age-related macular degeneration. METHODS: We examined the early images of indocyanine green videoangiography (v-ICGA) in 29 patients (29 eyes) with CNV, in whom feeder vessels could be identified by v-ICGA. The v-ICGA images were installed in a personal computer. With original software, optical density measurements were performed for the determination of dye-dilution curves. The flow velocity in a CNV feeder vessel was obtained by analyzing the dye-dilution curves. RESULTS: The mean flow velocity in feeder vessels was 33.8 +/- 32.5 mm/s. The flow velocity in feeder vessels of CNV with a diameter of 1.5 mm or larger was significantly higher than that in feeder vessels of CNV with a diameter smaller than 1.5 mm (P <.05, unpaired t-test). CONCLUSIONS: The flow velocity in CNV feeder vessels can be measured with v-ICGA and a computer-based image analysis system. This system would be useful in the evaluation of choroidal circulation.

Aged↗
PubMed1999

A prospective study of endoluminal ultrasound versus computerized tomography angiography for detecting crossing vessels at the ureteropelvic junction.

PURPOSE: Crossing vessels at the ureteropelvic junction are associated with bleeding complications and a higher risk of failure after endopyelotomy. We compared computerized tomography (CT) angiography and endoluminal ultrasound for detecting crossing vessels before planned endopyelotomy. MATERIALS AND METHODS: Preoperatively patients underwent CT angiography. Intraoperative evaluation included retrograde ureteropyelography, endoluminal ultrasound and ureteroscopy. Intraoperative findings were used to direct treatment. RESULTS: Endoluminal ultrasound detected 19 crossing vessels in 14 of 20 patients (70%), while CT detected 9 crossing vessels in 7 (35%). Endoluminal ultrasound identified a septum between the ureter and renal pelvis in 7 patients (35%) but CT demonstrated none. On the basis of imaging findings we selected 5 patients for pyeloplasty, and endoluminal ultrasound accurately predicted the absence or presence of crossing vessels in all 5. CT angiography was accurate in 3 patients. However, in 2 patients a total of 4 vessels were missed by CT. A total of 15 patients underwent endopyelotomy with no bleeding complications. The presence or absence of a septum on endoluminal ultrasound was confirmed in all patients. Imaging findings altered the treatment chosen in 4 patients and changed the direction of the incision at the ureteropelvic junction in another 4. Clinical and radiographic success was achieved in all 13 patients (100%) with adequate followup. CONCLUSIONS: Endoluminal ultrasound was more sensitive than CT angiography for identifying crossing vessels and septa. Treatment based on endoluminal ultrasound findings may decrease complications and improve the results of minimally invasive treatment for ureteropelvic junction obstruction.

Adolescent↗
PubMed1997

Three-dimensional imaging for presentation of the causative vessels in patients with hemifacial spasm and trigeminal neuralgia.

BACKGROUND: In patients with hemifacial spasm and trigeminal neuralgia, preoperative detection of the relationship between the blood vessels and the cranial nerves involved is essential. METHODS: We studied the causative vessels in 20 patients with hemifacial spasm and six patients with trigeminal neuralgia by means of magnetic resonance (MR) imaging with spoiled gradient recalled acquisition in the steady state (SPGR), MR angiography, and three-dimensional (3-D) imaging reconstructed from the data of SPGR MR imaging by the surface rendering method at a workstation. RESULTS: In all patients, the preoperative SPGR MR images demonstrated that the causative vessels compressed or were in contact with the root exit or root entry zone (REZ) of the facial or trigeminal nerve. These causative vessels were identified by inspection of the MR angiographic and 3-D images. The 3-D images provided clear information as to the anatomic relationship between the causative vessels and the REZ of these nerves. These findings were corroborated by the intraoperative findings. The symptoms were completely relieved after surgery in 18 of the patients with hemifacial spasm and in all six patients with trigeminal neuralgia. In all patients, sufficient decompression was depicted on the postoperative SPGR MR images at the causative vessels and the REZ of the nerve. CONCLUSION: SPGR MR images, MR angiography, and 3-D images are useful for the identification of the causative vessels in patients with hemifacial spasm or trigeminal neuralgia. The 3-D images are particularly useful for the simulation planning of the operative procedure.

Adult↗
PubMed2004

Segmentation of vessels from mammograms using a deformable model.

Vessel extraction is a fundamental step in certain medical imaging applications such as angiograms. Different methods are available to segment vessels in medical images, but they are not fully automated (initial vessel points are required) or they are very sensitive to noise in the image. Unfortunately, the presence of noise, the variability of the background, and the low and varying contrast of vessels in many imaging modalities such as mammograms, makes it quite difficult to obtain reliable fully automatic or even semi-automatic vessel detection procedures. In this paper a fully automatic algorithm for the extraction of vessels in noisy medical images is presented and validated for mammograms. The main issue in this research is the negative influence of noise on segmentation algorithms. A two-stage procedure was designed for noise reduction. First, a global approach phase including edge detection and thresholding is applied. Then, the local approach phase performs vessel segmentation using a deformable model with a new energy term that reduces the noise still remaining in the image from the first stage. Experimental results on mammograms show that this method has an excellent performance level in terms of accuracy, sensitivity, and specificity. The computation time also makes it suitable for real-time applications within a clinical environment.

Algorithms↗
PubMed2004

Electrical lumped model for arterial vessel beds.

Numerous electrical analog models of the circulatory system have been proposed. However, conventional models are either too simple, focusing exclusively on heart function, or overly complex, characterizing arteries in excessive detail. The vessel beds, which comprise arteries, capillaries and veins, are well known to be responsible for most of the pressure drop in blood pressure and to dominate the draining of blood flow. Consequently, electrical analog models of the circulatory system should pay more attention to the vessel beds. This investigation divided the arterial system into several aortic segments with vessel beds, and proposed a model that used electrical lumped elements to represent the vessel beds. The model was adopted to simulate blood pressure propagation by considering each vessel bed as an isolated subsystem. The transfer function between the terminals of isolated subsystems was used to identify the electrical components of the lumped elements that characterized the vessel beds. Simulation results reveal that the compliance and impedance of the vessel beds are larger than in previous models that focused on the aorta or arteries. The proposed electrical lumped model could deal with much more information than the simple models due to the lumped element structure. Furthermore, its isolated subsystem approach also makes the proposed model significantly easier to use than the complex models.

Arteries↗
PubMed2004

[Visudyne photodynamic therapy and feeder vessel occlusion: rationale of a synergistic association and clinical options].

PURPOSE: Visudyne photodynamic therapy (PDT) has provided considerable improvement in patient care of subfoveal choroidal neovascularization (CNV). Patients tend to loose vision for a few months after the initial treatment, but the 4-year proven stability in vision most often provides an acceptable quality of life, sometimes with additional low vision rehabilitation. The initial visual acuity loss, borderline cost-effectiveness, and subgroups of patients not responding to PDT warrant improving the symptomatic treatment of subfoveal CNV. Today, the most tempting solution would be to combine PDT with an occlusion of the feeder vessel (FV). METHODS: Two patients are described in whom the feeder vessel was occluded using modifications of the classic PDT treatment method. The FV was identified in both patients using fluorescein and indocyanine green angiographies at a recorded video rate using a modified scanning laser ophthalmoscope (Rodenstock SLO). The feeder vessel of the first patient was occluded by minimal photocoagulation immediately after a Visudyne PDT treatment in order to take advantage of the reduced blood flow within the feeder vessel. The second patient presenting a subfoveal FV was treated using a modified PDT treatment called feeder-vessel PDT. The photosensitizing agent was activated by a first classic spot covering the lesion, followed immediately by a small spot focused on the feeder vessel. RESULTS: Both subfoveal CNVs were successfully and selectively occluded and some visual acuity was gained following the treatment. CONCLUSION: Occlusion of the feeder vessel is an appealing clinical option that is complementary to Visudyne PDT. Both treatment methods presented here could provide additional options to close subfoveal CNV with an optimal efficacy-risk ratio.

Angiography↗
PubMed1999

The effect of hemodynamics, vessel wall compliance and hematocrit on ultrasonic Doppler power: an in vitro study.

Previous in vitro studies in rigid tubes under pulsatile flow conditions have reported a lack of a cyclic variation in blood echogenicity that contradicts in vivo results. To investigate whether or not these variations can be attributed to the compliance of the vessel wall, a series of in vitro experiments with compliant tubes, under pulsatile flow conditions, was performed. Two important factors that may affect the Doppler power were investigated: 1. the dependence on hematocrit and 2. the effect of the vessel wall elasticity. In the present study, it is shown that, at the low beat rates, the peak of the mean Doppler power within the flow cycle depends on the vessel wall compliance. When the vessel becomes more compliant, the peak is shifted from the early to the late systole. Additionally, there is a correlation between the power peak and hematocrit that is more evident in compliant vessels. At a higher pulsation rate of 37 beats/min, a different variation is observed. A drop in the power occurs near peak systole in compliant tube experiments and is more pronounced as the vessel becomes more constricted. The observed power drop agrees with previously reported in vivo results, but is not seen in rigid tube experiments. The results of this study suggest that proper interpretation of cyclic variations in Doppler power requires a knowledge of hemodynamic parameters, such as the modulus of elasticity of the vessel wall, propagation velocity or, possibly, the phase angle of input impedance.

Animals↗
PubMed2000

A study of the behaviour of a protected vessel containing LPG during pool fire engulfment.

Theoretical and experimental investigations of various methods for protection against fires of vessels containing liquefied petroleum gases (LPG) (safety relief valves, intumescent fire retardant coatings, thermal isolation) have been carried out. A simple mathematical model has been proposed, which describes dependences of various parameters on time. These parameters are temperature, pressure and mass of LPG, temperatures of the vessel's walls and thermal protection layer. The case of total fire engulfment of the vessel with LPG was considered. Experiments have been executed, which were aimed on the investigation of the behaviour of vessels with LPG (50 l), equipped with protective devices during total fire engulfment. It was found out that the safety valve prevented an explosion of the vessels without any other protective measures. The presence of the intumescent fire retardant coating caused a significant delay in operation of the safety valve. A rather good agreement between the theoretical and experimental data was obtained. It has been revealed that the considered methods for protection of LPG vessels are promising in regard to prevention of explosions in these vessels at the fire engulfment.

Accidents, Occupational↗
PubMed2000

Improved phase-contrast flow quantification by three-dimensional vessel localization.

In this paper, a method of three-dimensional (3D) vessel localization is presented to allow the identification of a vessel of interest, the selection of a vessel segment, and the determination of a slice orientation to improve the accuracy of phase-contrast magnetic resonance (PCMR) angiography. A marching-cube surface-rendering algorithm was used to reconstruct the 3D vasculature. Surface-rendering was obtained using an iso-surface value determined from a maximum intensity projection (MIP) image. This 3D vasculature was used to find a vessel of interest, select a vessel segment, and to determine the slice orientation perpendicular to the vessel axis. Volumetric flow rate (VFR) was obtained in a phantom model and in vivo using 3D localization with double oblique cine PCMR scanning. PCMR flow measurements in the phantom showed 5. 2% maximum error and a standard deviation of 9 mL/min during steady flow, 7.9% maximum error and a standard deviation of 13 mL/min during pulsatile flow compared with measurements using an ultrasonic transit-time flowmeter. PCMR VFR measurement error increased with misalignment at 10, 20, and 30 degrees oblique to the perpendicular slice in vitro and in vivo. The 3D localization technique allowed precise localization of the vessel of interest and optimal placement of the slice orientation for minimum error in flow measurements.

Blood Flow Velocity↗
PubMed1996

Possible mechanisms for an irregular vessel coagulation when long laser pulses are used in the treatment of port-wine stains.

The laser treatment of port-wine stains (PWS) has as a main aim the irreversible damage of ectatic vessels. Blood content of the subcutaneous venous plexus in PWS can be increased by a factor of seven or more, compared to that of the normal skin. The venous blood velocity ranges from 0.1-1 mm/s in capillaries to approximately 22 mm/s in larger vessels of about 300 microns in diameter. A PWS, selected for study, was irradiated with a multiline argon laser 488/515 nm wavelength, 1.5 W power, 200 ms pulse duration, 0.5 mm beam diameter and repetition frequency up to 5 Hz. Laser shots were placed adjacently in an area of 1 cm2. Using these parameters, in the case of dilated PWS vessels with an optical penetration depth and thermal diffusion length less than the diameter of the vessel, together with a transit time of blood across the irradiated spot less than the pulse duration, and estimating that during a pulsed laser emission of 200 ms, the blood has travelled a distance of 3-4 mm, there is a strong indication that hemodynamics during irradiation may influence the pattern of coagulation and agglutination. Thrombosis should occur in the case of small vessels and, in larger vessels, the coagulated blood will only partly fill the lumen. The structure developed in the vessel interior may also change continuously with time, as the coagulated material is progressively replaced by fibrotic tissue and the irregular agglutination pattern may be due to inhomogeneity in the absorbed optical energy.

Biophysical Phenomena↗
PubMed2004

Improvement of collateral vessels in the vicinity of gastric cardia after endoscopic variceal ligation therapy for esophageal varices.

BACKGROUND & AIMS: Endoscopic variceal ligation (EVL) therapy has been performed widely to treat or prevent variceal bleeding. We sought to examine the influence of EVL for esophageal varices on collateral vessels in the vicinity of gastric cardia. METHODS: In 42 patients with esophagogastric varices, conventional endoscopy and endoscopic ultrasonography with a 20-MHz probe (CUP-EUS) were performed before and at every 3 months after EVL for esophageal varices. By using conventional endoscopy, cardial variceal sizes were divided into 3 grades: F0, F1, and F2. The sizes of submucosal, perforating, and paracardial vessels at the cardia also were classified into 3 grades according to CUP-EUS findings. RESULTS: Conventional endoscopy showed cardial varices in 33 (79%) patients before and 23 (55%) patients at 3 months after the treatment (P < 0.05). CUP EUS showed that 29 (69%) patients had severe grade cardial submucosal vessels before EVL, but only 13 (31%) patients did after the treatment (P < 0.01). Nineteen (45%) patients had severe grade cardial perforating vessels before EVL, but only 4 (10%) patients did after the treatment (P < 0.001). Furthermore, patients with severe grade residual submucosal or perforating vessels at the cardia had shorter recurrence-free times of esophageal varices (P < 0.01, 0.05, respectively). CONCLUSIONS: Collateral vessels in the vicinity of gastric cardia were improved significantly after EVL, indicating that esophageal varices can be treated by EVL even though they connect with cardial varices. Furthermore, eradication of such collateral vessels by EVL may lead to longer recurrence-free status of esophageal varices.

Adult↗
PubMed2006

Targeted insult to subsurface cortical blood vessels using ultrashort laser pulses: three models of stroke.

We present a method to produce vascular disruptions within rat brain parenchyma that targets single microvessels. We used two-photon microscopy to image vascular architecture, to select a vessel for injury and to measure blood-flow dynamics. We irradiated the vessel with high-fluence, ultrashort laser pulses and achieved three forms of vascular insult. (i) Vessel rupture was induced at the highest optical energies; this provides a model for hemorrhage. (ii) Extravasation of blood components was induced near the lowest energies and was accompanied by maintained flow in the target vessel. (iii) An intravascular clot evolved when an extravasated vessel was further irradiated. Such clots dramatically impaired blood flow in downstream vessels, in which speeds dropped to as low as approximately 10% of baseline values. This demonstrates that a single blockage to a microvessel can lead to local cortical ischemia. Lastly, we show that hemodilution leads to a restoration of flow in secondary downstream vessels.

Animals↗
PubMed2002

Effects of histamine on the contractile and electrical activity in isolated lymphatic vessels of the guinea-pig mesentery.

1 The effect of histamine on the rate of lymphatic vessel constrictions and lymphatic smooth muscle membrane potential was examined in the guinea-pig mesentery. 2 Histamine (0.01-5 micro M) increased the frequency and decreased the amplitude of constrictions in lymphatic vessels under intraluminal perfusion. This response was accompanied by a depolarization of the smooth muscle membrane potential, an increase in the activity of spontaneous transient depolarizations (STDs), the proposed pacemaker for constrictions in these vessels, and an increase in the occurrence of action potentials. 3 Responses to histamine were inhibited by the H(1) receptor antagonist pyrilamine (0.2 micro M), but unaffected by NO synthase inhibition with N(G)-nitro L-arginine (L-NOARG, 100 micro M) and lysis of the endothelium. 4 In about 50% of the vessels, a decrease in constriction frequency, STD activity and a smooth muscle hyperpolarization were observed in response to dimaprit (10 micro M), suggesting the presence of H(2) receptors. These vessels had also a significantly lower basal contractile rate. Lymphatic vessel pumping was not affected by R-alpha-methylhistamine (10-50 micro M), ruling out a role for H(3) receptor stimulation in the histamine response. 5 The present results suggest a direct action of histamine on the lymphatic smooth muscle via stimulation of H(1) (and in some vessels H(2)) receptors. H(1) receptors enhance and H(2) receptors slow down lymphatic pumping, the dominant effect being an increased contractile activity. Correlation of these effects with histamine-induced changes in membrane potential and STD activity suggests the involvement of these electrical changes in the initiation of the contractile response.

Animals↗
PubMed1979

Effect of age on noradrenaline sensitivity of mesenteric resistance vessels in spontaneously hypertensive and Wistar-Kyoto rats.

1. We have compared the noradrenaline sensitivity of 150 micron arterial resistance vessels taken from a specific place in the mesenteric bed of spontaneously hypertensive (SH) rats and of control Wistar-Kyoto (WK) rats at three ages: 6 weeks, 12 weeks and 24 weeks. 2. The noradrenaline sensitivity of the vessels under normal conditions was the same at all ages in both SH and WK rats (ED50 about 3 mu mol/l). 3. After addition of cocaine (which inhibits the uptake of noradrenaline in the nerve terminals) all vessels became more sensitive to noradrenaline, but at all ages the increase in sensitivity was greater in the vessels of SH rats, suggesting that the smooth muscle cells in these vessels had a greater intrinsic noradrenaline sensitivity than the vessels of WK rats. 4. Since elevation of the blood pressure in the SH rats occurs mainly between the ages of 6 and 12 weeks, the results suggest that the greater intrinsic smooth muscle cell sensitivity of the SH rat vessels is a factor which is amongst the primary factors responsible for the development of hypertension in the SH rat.

Aging↗
PubMed1980

Effect of sodium-potassium-dependent ATPase inhibition on noradrenaline-activated calcium sensitivity of mesenteric resistance vessels in adult spontaneously hypertensive rats.

1. We have investigated the noradrenaline-activated calcium sensitivity of 150 micrometer mesenteric resistance blood vessels from spontaneously hypertensive and control Wistar-Kyoto rats. 2. Under control conditions the spontaneously hypertensive rat blood vessels had a greater calcium sensitivity than the Wistar-Kyoto rat vessels. 3. In the presence of 1 mmol of ouabain/l, a treatment known to inhibit the sodium-potassium-dependent ATPase, the responses of the spontaneously hypertensive rat blood vessels were reduced more than those of the Wistar-Kyoto rat blood vessels, so that the responses of spontaneously hypertensive rat and Wistar-Kyoto rat blood vessels were then similar. 4. Similar results were obtained by removing external potassium, a procedure which should also inhibit the sodium-potassium-ATPase. 5. The results suggest that the greater noradrenaline-activated calcium sensitivity of spontaneously hypertensive rat blood vessels may be associated with an increased sodium-potassium-ATPase activity.

Animals↗