Propofol increases vascular relaxation in aging rats chronically treated with the angiotensin-converting enzyme inhibitor captopril

Distinct Effects of Sevoflurane and Propofol on Vascular Permeability In Vitro and in a Mouse Model

BACKGROUND

General anesthetics may substantially influence endothelium function, potentially affecting outcomes of surgical patients, but their effects are unclear. Here, the authors studied a commonly used inhaled anesthetic, sevoflurane, and an intravenous anesthetic, propofol, on vascular endothelial permeability using multiple in vitro assays and a mouse model.

METHODS

Human umbilical vein endothelial cells and mouse pulmonary endothelial cells (MPECs) were used for in vitro models to test the effect of anesthetics on endothelial permeability. The effect of anesthetics on pulmonary vascular leakage was analyzed using AngioSense 750 (PerkinElmer, USA) fluorescent tracer and rhodamine-labeled 3-kD dextran in a mouse model. Downstream targets were identified using RNA sequencing and confirmed by quantitative real-time polymerase chain reaction and Western blot.

RESULTS

Sevoflurane at clinically relevant concentrations disrupted the endothelial monolayer formed by human umbilical vein endothelial cells and MPECs in transwell permeability models. Sevoflurane, but not propofol, induced a 1.8-fold increase of AngioSense dye accumulation in mouse lung over control, indicating pulmonary vascular leakage in the sevoflurane group. RNA sequencing analysis, quantitative real-time polymerase chain reaction, and Western blot analysis revealed that sevoflurane induced the expression and activation of hypoxia-inducible factor 1α (HIF-1α) in vitro and in vivo . The activation of HIF-1α led to the increased expression of its downstream vascular endothelial growth factor (VEGF). The knockdown of HIF-1α restored the change of endothelial permeability and abolished the increase of VEGF induced by sevoflurane in MPECs.

CONCLUSIONS

The authors' results demonstrate that sevoflurane increased endothelial and pulmonary vascular permeability via HIF-1α and VEGF. Propofol had no significant effect on the permeability of endothelium.

Comparison the Effect of Granisetron and Dexamethasone on Intravenous Propofol Pain

Background:

The incidence of propofol injection pain during induction of general anesthesia varies from 28% to 90%. This prospective, randomized, double-blind, placebo-controlled study evaluated the effect of dexamethasone and granisetron for reducing the incidence and severity of propofol injection pain.

Materials and Methods:

A total of 227 female subjects received 5 mL of preservative-free saline, 1 mg granisetron (5 ml), or 0.15 mg/kg of dexamethasone (5 ml), intravenously, following exsanguination and occlusion of the veins of the arm. This was followed by a 0.5 mg/kg injection of propofol. Pain scores and intensity of pain recorded immediately following the injection of propofol. Hemodynamic parameters and O₂ sat were recorded 1, 3, 5, and 10 min after propofol injection.

Results:

The incidence pain following the injection of propofol was significantly decreased with both granisetron and dexamethasone (50.7% and 49.4%). Mean pain score in granisetron group was 3.16 ± 1.23, dexamethasone was 2.73 ± 1.03, and in saline group was 4.82 ± 1.73 (P = 0.001). Mean pain intensity in granisetron group was 1.16 ± 0.18, dexamethasone was 1.26 ± 0.14, and in saline group was 2.2 ± 0.99 (P = 0.001). There were no differences in either mean arterial pressure or O₂ Sate at any time point after drugs injection among the groups. There was a significant difference in pulse rate in third minutes between three groups and in the group who received granisetron was lesser (P = 0.04).

Conclusion:

Pretreatment with intravenous granisetron (1 mg) and dexamethasone (0.15 mg/kg) before injection of propofol is effective and safe in reducing the incidence and severity of pain due to propofol injection.

Angiotensin converting enzyme inhibitors enhance the hypotensive effects of propofol by increasing nitric oxide production

Propofol anesthesia is usually accompanied by hypotension. Studies have shown that the hypotensive effects of propofol increase in patients treated with angiotensin-converting enzyme inhibitors (ACEi). Given that both propofol and ACEi affect nitric oxide (NO) signaling, the present study tested the hypothesis that ACEi treatment induces pronounced hypotensive responses to propofol by increasing NO bioavailability. In this study we evaluated 65 patients, divided into three groups: hypertensive patients chronically treated with ACEi (HT-ACEi; n = 21), hypertensive patients treated with other antihypertensive drugs instead of ACEi, such as angiotensin II receptor blockers, β-blockers or diuretics (HT; n = 21) and healthy normotensive subjects (NT; n = 23). Venous blood samples were collected at baseline and after 10min of anesthesia with propofol 2mg/kg administrated intravenously by bolus injection. Hemodynamic parameters were recorded at each blood sample collection. Nitrite levels were determined by using an ozone-based chemiluminescence assay, while NOx (nitrites+nitrates) levels were measured by using the Griess reaction. Additionally, experimental approaches were used to validate our clinical findings. Higher decreases in blood pressure after propofol anesthesia were observed in HT-ACEi group as compared with those found in NT and HT groups. Consistently, rats treated with the ACEi enalapril showed more intense hypotensive responses to propofol. The hypotensive effects of propofol were associated with increased NO production in both clinical and experimental approaches. Enhanced increases in nitrite levels after propofol anesthesia were observed in HT-ACEi patients compared with NT and HT groups. Accordingly, rats treated with enalapril showed increased vascular NO formation after propofol anesthesia compared with rats receiving vehicle. Our data show that ACEi enhance the hypotensive responses to propofol anesthesia and increase nitrite concentrations. These findings suggest that increased NO bioavailability may account for the enhanced hypotensive effects of propofol in ACEi-treated patients.

Propofol induces excessive vasodilation of aortic rings by inhibiting protein kinase Cβ2 and θ in spontaneously hypertensive rats

BACKGROUND AND PURPOSE

Exaggerated hypotension following administration of propofol is strongly predicted in patients with hypertension. Increased PKCs play a crucial role in regulating vascular tone. We studied whether propofol induces vasodilation by inhibiting increased PKC activity in spontaneously hypertensive rats (SHRs) and, if so, whether contractile Ca²⁺ sensitization pathways and filamentous-globular (F/G) actin dynamics were involved.

EXPERIMENTAL APPROACH

Rings of thoracic aorta, denuded of endothelium, from normotensive Wistar-Kyoto (WKY) rats and SHR were prepared for functional studies. Expression and activity of PKCs in vascular smooth muscle (VSM) cells were determined by Western blot analysis and elisa respectively. Phosphorylation of the key proteins in PKC Ca²⁺ sensitization pathways was also examined. Actin polymerization was evaluated by differential centrifugation to probe G- and F-actin content.

KEY RESULTS

Basal expression and activity of PKCβ2 and PKCθ were increased in aortic VSMs of SHR, compared with those from WKY rats. Vasorelaxation of SHR aortas by propofol was markedly attenuated by LY333531 (a specific PKCβ inhibitor) or the PKCθ pseudo-substrate inhibitor. Furthermore, noradrenaline-enhanced phosphorylation, and the translocation of PKCβ2 and PKCθ, was inhibited by propofol, with decreased actin polymerization and PKCβ2-mediated Ca²⁺ sensitization pathway in SHR aortas.

CONCLUSION AND IMPLICATIONS

Propofol suppressed increased PKCβ2 and PKCθ activity, which was partly responsible for exaggerated vasodilation in SHR. This suppression results in inhibition of actin polymerization, as well as that of the PKCβ2- but not PKCθ-mediated, Ca²⁺ sensitization pathway. These data provide a novel explanation for the unwanted side effects of propofol.

Quinapril decreases antifibrinolytic and prooxidative potential of propofol in arterial thrombosis in hypertensive rats

Angiotensin converting enzyme inhibitors and propofol both exert hypotensive action and may affect hemostasis. We investigated the influence of quinapril and propofol on hemodynamics and hemostasis in renal-hypertensive rats with induced arterial thrombosis. Two-kidney, one clip hypertensive rats were treated with quinapril (3.0 mg/kg for 10 days), and then received propofol infusion (15 mg/kg/h) during ongoing arterial thrombosis. The hemodynamic and hemostatic parameters were assayed. Quinapril exerted a hypotensive effect increasing after propofol infusion. Quinapril showed an antithrombotic effect with the platelet adhesion reduction, fibrinolysis enhancement and oxidative stress reduction. Propofol did not influence thrombosis; however, it inhibited fibrinolysis and showed prooxidative action. The effect of propofol on fibrinolysis and oxidative stress was significantly lower in quinapril-pretreated rats. Mortality was increased among rats treated with both drugs together. Our study demonstrates that pretreatment with quinapril reduced the adverse effects of propofol on hemostasis. Unfortunately, co-administration of both drugs potentiated hypotension in rats, which corresponds to higher mortality.

Optimal perioperative management of arterial blood pressure

Perioperative blood pressure management is a key factor of patient care for anesthetists, as perioperative hemodynamic instability is associated with cardiovascular complications. Hypertension is an independent predictive factor of cardiac adverse events in noncardiac surgery. Intraoperative hypotension is one of the most encountered factors associated with death related to anesthesia. In the preoperative setting, the majority of antihypertensive medications should be continued until surgery. Only renin-angiotensin system antagonists may be stopped. Hypertension, especially in the case of mild to moderate hypertension, is not a cause for delaying surgery. During the intraoperative period, anesthesia leads to hypotension. Hypotension episodes should be promptly treated by intravenous vasopressors, and according to their etiology. In the postoperative setting, hypertension predominates. Continuation of antihypertensive medications and postoperative care may be insufficient. In these cases, intravenous antihypertensive treatments are used to control blood pressure elevation.

The effect of intravenous dexamethasone and lidocaine on propofol-induced vascular pain: a randomized double-blinded placebo-controlled trial

Background. The mechanism for pain associated with intravenous administration of propofol is believed to be related to the release of nitric oxide. We hypothesized that pain following propofol injection would be reduced by pretreatment with dexamethasone. Methods. One hundred fourteen female subjects received 5 mL of preservative-free saline, 0.5 mg·kg⁻¹ of lignocaine hydrochloride 10 mg·mL⁻¹ or 0.25 mg·kg⁻¹ of dexamethasone, intravenously, following exsanguination and occlusion of the veins of the arm. This was followed by a 0.5 mg·kg⁻¹ injection of propofol. Pain scores, facial grimacing, arm withdrawal, and vocalization were recorded prior to and at 15 and 30 seconds following the injection of propofol. Results. The incidence of moderate to severe pain following the injection of propofol was significantly decreased with both lidocaine and dexamethasone. Hand withdrawal was also significantly decreased in comparison to saline. Conclusion. Low dose dexamethasone is commonly used as an antiemetic, and, in larger doses, it has been demonstrated to provide prolonged postoperative analgesia. At higher analgesic doses, dexamethasone may also reduce pain associated with the injection of propofol. This effect is probably related to the effect of the steroid on nitric oxide production associated with intravenous propofol injection.