Effect of normovolemic hematocrit changes on blood pressure and flow

Influence of a Decrease in Blood Viscosity on Arterial Pressure in Normotensive and Spontaneously Hypertensive Rats

We investigated the effect of a decrease in blood viscosity on the mean BP during isovolumic hemodilution and vasodilating activity of the endothelium in normotensive Wistar rats and spontaneously hypertensive rats (SHR). Blood viscosity was reduced by isovolumic hemodilution (replacement of 10% of circulating blood with an equal volume of plasma). Hemodilution caused the same reduction in blood viscosity by 16% in both groups of rats. In Wistar rats, a decrease in blood viscosity did not significantly change in the mean BP; no significant correlations between blood viscosity and mean BP were observed before and after hemodilution. In SHR, a decrease in blood viscosity led to a significant decrease in the mean BP by 18%. Correlations were found between the mean BP and blood viscosity in SHR before (r=0.63; p=0.028) and after (r=0.71; p=0.009) isovolumic hemodilution. In SHR, a decrease in the index of vasodilating activity of the endothelium due to a decrease in the vasodilatory response to intravenous administration of the endothelium-dependent vasodilator acetylcholine was revealed. In SHR, BP passively follows the change, in this case, the decrease in blood viscosity, which attests to impaired BP regulation in response to changes in shear stress on the vascular endothelium caused by the development of endothelial dysfunction in hypertensive animals.

Inhibition of circulating dipeptidyl-peptidase 3 restores cardiac function in a sepsis-induced model in rats: A proof of concept study

Sepsis is a global economic and health burden. Dipeptidyl peptidase 3 (DPP3) is elevated in the plasma of septic patients. The highest levels of circulating DPP3 (cDPP3) are found in non-survivor septic shock patients. The aim of this study was to evaluate the benefits of inhibiting cDPP3 by a specific antibody, Procizumab (PCZ), on cardiac function in an experimental model of sepsis, the caecal ligature and puncture (CLP) model. Rats were monitored by invasive blood pressure and echocardiography. Results are presented as mean ± SD, with p <0.05 considered significant. PCZ rapidly restored left ventricular shortening fraction (from 39 ± 4% to 51 ± 2% before and 30 min after PCZ administration (p = 0.004)). Cardiac output and stroke volume were higher in the CLP + PCZ group when compared to the CLP + PBS group (152 ± 33 mL/min vs 97 ± 25 mL/min (p = 0.0079), and 0.5 ± 0.1 mL vs 0.3 ± 1.0 mL (p = 0.009), respectively) with a markedly reduced plasma DPP3 activity (138 ± 70 U/L in CLP + PCZ group versus 735 ± 255 U/L (p = 0.048) in the CLP + PBS group). Of note, PCZ rapidly reduced oxidative stress in the heart of the CLP + PCZ group when compared to those of the CLP + PBS group (13.3 ± 8.2 vs 6.2 ± 2.5 UI, p = 0.005, 120 min after administration, respectively). Our study demonstrates that inhibition of cDPP3 by PCZ restored altered cardiac function during sepsis in rats.

Cell seeding accelerates the vascularization of tissue engineering constructs in hypertensive mice

Rapid blood vessel ingrowth into transplanted constructs represents the key requirement for successful tissue engineering. Seeding three-dimensional scaffolds with suitable cells is an approved technique for this challenge. Since a plethora of patients suffer from widespread diseases that limit the capacity of neoangiogenesis (e.g., hypertension), we investigated the incorporation of cell-seeded poly-L-lactide-co-glycolide scaffolds in hypertensive (BPH/2J, group A) and nonhypertensive (BPN/3J, group B) mice. Collagen-coated scaffolds (A1 and B1) were additionally seeded with osteoblast-like (A2 and B2) and mesenchymal stem cells (A3 and B3). After implantation into dorsal skinfold chambers, inflammation and newly formed microvessels were measured using repetitive intravital fluorescence microscopy for 2 weeks. Apart from a weak inflammatory response in all groups, significantly increased microvascular densities were found in cell-seeded scaffolds (day 14, A2: 192 ± 12 cm/cm², A3: 194 ± 10 cm/cm², B2: 249 ± 19 cm/cm², B3: 264 ± 17 cm/cm²) when compared with controls (A1: 129 ± 10 cm/cm², B1: 185 ± 8 cm/cm²). In this context, hypertensive mice showed reduced neoangiogenesis in comparison with nonhypertensive animals. Therefore, seeding approved scaffolds with organ-specific or pluripotent cells is a very promising technique for tissue engineering in hypertensive organisms.

The use of smartphone-obtained images to extrapolate canine packed cell volume

OBJECTIVE

To determine whether a smartphone-obtained image can be used to extrapolate the PCV of canine blood samples.

DESIGN

Prospective study of surplus blood obtained from clinical cases.

SETTING

University teaching hospital.

INTERVENTIONS

Blood samples were placed on filter paper, and images were obtained with a smartphone in different environments. These results were then compared to the PCV measurements on the same samples following the World Health Organization guidelines.

MEASUREMENTS

Sixty-nine samples were assessed and identified that smartphone images, obtained in a controlled environment, were able to predict the PCV of the samples. This prediction was most accurate when assessing samples of a normal erythroid mass or polycythemic samples.

CONCLUSIONS

The results of this study suggest that smartphone-obtained images do have a utility in predicting canine PCV. If this can be incorporated into a smartphone application, there would be scope to use this in low resource settings.

Influence of acute reduction of blood viscosity on endothelial function

BACKGROUND

The relationship between blood viscosity (BV) and endothelial function is rather complex. An increase in BV causes an increase in blood flow resistance, with negative hemodynamic effects; on the other hand, a moderate increase in BV causes an increase in wall stress shear (WSS), and consequent beneficial effects. As a matter of fact, the effect of changes in BV on endothelial function is not yet clear.

OBJECTIVES

Aim of the present study was to evaluate in-vivo the effects of the acute reduction in BV on endothelial function, in healthy male subjects.

METHODS

Fourteen healthy male blood donors were studied before and 48 hours after blood donation. Blood and plasma viscosity were measured at 37C° with a cone-plate viscometer. Endothelial function was evaluated through flow mediated vasodilation (FMD).

RESULTS

Blood viscosity was reduced after blood donation (BV225 (cP) 4.53±0.59 vs.4.18±0.31, p < 0.05). FMD 50 s after cuff deflation was unchanged: 6.23±3.84 vs. 6.62±4.81, p = NS. The vasodilation, however, lasted longer and the area under the curve of FMD was significantly increased: 8.74±8.77 vs.16.14±8.65, p < 0.005.

CONCLUSIONS

The present results demonstrate that the acute reduction of BV prolongs vasodilation, without affecting the amount of vasodilatation, possibly as adaptive reaction allowing more time for oxygen release.

Adrecizumab, a non-neutralizing anti-adrenomedullin antibody, improves haemodynamics and attenuates myocardial oxidative stress in septic rats

Background

Sepsis still represents a major health issue, with persistent high morbidity and mortality rates. Cardiovascular dysfunction occurs frequently during sepsis. Adrenomedullin has been identified as a key mediator in vascular tone regulation. A non-neutralizing anti-adrenomedullin antibody, Adrecizumab, may improve haemodynamic dysfunction during caecal ligation and puncture-induced septic shock in a murine model. Our objective was to determine the role of Adrecizumab on haemodynamics in a rat model of sepsis.

Methods

For the induction of sepsis, caecal ligation and puncture were performed in Wistar male rats. Single blinded administration of Adrecizumab (2 mg/kg) or placebo was injected i.v. 24 h after the surgery, and norepinephrine was infused as the standard of care. There were > 7 animals per group. Invasive blood pressure and cardiac function (by echocardiography) were assessed until 3 h after Adrecizumab injection.

Results

A single therapeutic injection of Adrecizumab in septic rats induced rapid haemodynamic benefits with an increase in systolic blood pressure in septic-Adrecizumab rats versus untreated-septic rats (p = 0.049). The shortening fraction did not differ between the untreated-septic and septic-Adrecizumab groups. However, cardiac output increased during the 3 h after a single dose of Adrecizumab compared to untreated septic rats (p = 0.006). A single dose of Adrecizumab resulted in similar haemodynamics to the continuous administration of norepinephrine.

Three hours after a single injection of Adrecizumab, there was no change in the inflammatory phenotype (TNFα, IL-10) in the hearts of the septic rats. By contrast, 3 h after a single Adrecizumab injection, free-radical production decreased in the hearts of septic-Adrecizumab vs untreated septic rats (p < 0.05).

Conclusions

In a rat model of sepsis, a single therapeutic injection of Adrecizumab rapidly restored haemodynamic parameters and blunted myocardial oxidative stress. Currently, a proof-of-concept and dose-finding phase II trial (Adrenoss-2) is ongoing in patients with septic shock and elevated concentrations of circulating bio-adrenomedullin.

Electronic supplementary material

The online version of this article (10.1186/s40635-019-0255-0) contains supplementary material, which is available to authorized users.

No effect on the short-term of a decrease in blood viscosity on insulin resistance

BACKGROUND

Blood viscosity (BV) might influence glucose delivery to peripheral tissues and play an important role in insulin resistance and diabetes mellitus. However, the exact relationship between BV and insulin resistance is not yet clear.

OBJECTIVES

Aim of the present study is to evaluate the effects of the acute reduction in BV on insulin resistance, in healthy male subjects.

METHODS

Fifteen healthy male blood donors have been studied before and 48 hours after blood donation. Blood and plasma viscosity have been measured at 37°C with a cone-plate viscometer. Insulin resistance has been evaluated by euglycemic/hyperinsulinemic clamp in eight subjects, and by iHOMA2 Index in further seven subjects.

RESULTS

Blood viscosity was markedly reduced after blood donation (BV225 (cP) 4.53 ± 0.59 vs. 4.18 ± 0.31, p < 0.05). Insulin resistance was unchanged: MFFM clamp: 5.6 ± 4.5vs. 4.4 ± 2.2 and iHOMA2 Index 1.2 ± 0.6 vs. 1.2 ± 0.5, before vs. after respectively, p = NS. Blood pressure and lipids were unchanged after blood donation.

CONCLUSIONS

The present results demonstrate that acute reduction of BV in healthy male subjects does not change the insulin resistance, measured using both euglycemic/hyperinsulinemic clamp and iHOMA2 Index. Further intervention studies are needed to assess the effect that the reduction in BV can have in subjects with insulin resistance.

Water in the human body: An anesthesiologist's perspective on the connection between physicochemical properties of water and physiologic relevance

The unique structure and multifaceted physicochemical properties of the water molecule, in addition to its universal presence in body compartments, make water a key player in multiple biological processes in human physiology. Since anesthesiologists deal with physiologic processes where water molecules are critical at different levels, and administer medications whose pharmacokinetics and pharmacodynamics depend on interaction with water molecules, we consider that exploration of basic science aspects related to water and its role in physiology and pharmacology is relevant to the practice of anesthesiology. The purpose of this paper is to delineate the physicochemical basis of water that are critical in enabling it to support various homeostatic processes. The role of water in the formation of solutions, modulation of surface tension and in homeostasis of body temperature, acid-base status and osmolarity, is analyzed. Relevance of molecular water interactions to the anesthesiologist is not limited to the realm of physiology and pathophysiology. Deep knowledge of the importance of water in volatile anesthetic effects on neurons opens a window to a new comprehensive understanding of complex cellular mechanisms underlying the practice of anesthesiology.