The Effects of Propofol and Thiopental on Nitric Oxide Production and Release in Erythrocytes

Hypotension is frequently encountered during the use of these commonly used intravenous anaesthetic agents (thiopental and propofol). This is thought to be a consequence of their effects on the sympathetic nervous system, myocardial contractility or vascular tone. However, propofol causes a greater fall in systemic arterial blood pressure than any other drug used for induction of anaesthesia. Propofol causes profound vasodilation, whereas its myocardial depressant effect is not clear. The vasodilatation occurs in both arterial and venous systems. The decrease in systemic arterial blood pressure after thiopental induction is mainly due to peripheral vasodilatation caused by depression of the medullary vasomotor centre and inhibition of the sympathetic nervous system. However, how this peripheral vasodilator effect occurs after both drugs and which mediators accompany it have not yet been fully elucidated. In previous studies, it has been emphasised that systemic vasodilation may be related with increased formation of nitric oxide (NO), a small gaseous and lipophilic molecule which plays an important role in the regulation of vascular homeostasis and haemoregulation. It is important to elucidate the mechanisms that may mediate thiopental- and propofol-mediated vasodilatation in future studies in order to help the methods and treatments that can be developed to prevent hypotension caused by these drugs, which are widely used in clinical practice. Therefore, the aim of this study was to investigate the effects of thiopental and profol on erythrocyte NO synthase activity and erythrocyte-mediated NO release.

Study Overview

• Status: Completed
• Conditions: Effect of Drug
• Intervention / Treatment: Drug: Thiopental; Drug: Propofol

Detailed Description

Male patients aged 18-45 years with ASA (American Society of Anaesthesiologists) class I (normal, healthy person without any disease or systemic problem other than surgical pathology that does not cause a systemic disorder) who applied to the anaesthesiology and reanimation clinic outpatient clinic for preoperative preparation were planned to be included in the study. Women, patients with ASA class >1, patients with known thiopental/propofol allergy and patients outside the age range of 18-45 years were excluded from the study. Venous blood samples will be taken from the patients included in the study and incubated with thiopental and propofol (dose: 100, 250, 500 and 1000µM) after appropriate procedures in the laboratory environment. . After incubation, all resuspensions will be subjected to flow cytometric analysis to evaluate erythrocyte NO synthase activity and erythrocyte-mediated NO release.All patients included in the study will be informed and their written and verbal consent will be obtained.

• Study Type: Interventional
• Enrollment (Actual): 12
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Turkey
  • Antalya, Turkey
    • Akdeniz University School of Medicine, Department of Anesthesiology and Intensive Care, Turkey

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Male patients
• Aged 18-45 years
• ASA (American Society of Anaesthesiologists) class I (normal, healthy person without any disease or systemic problem other than surgical pathology that does not cause a systemic disorder)

Exclusion Criteria:

• Women patients
• ASA class >1
• Patients with known thiopental/propofol allergy
• Patients outside the age range of 18-45 years

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Other
• Allocation: Non-Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Thiopental; Venous blood samples will be taken from the patients included in the study and incubated with thiopental (dose: 100, 250, 500 and 1000µM) after appropriate procedures in the laboratory environment. . After incubation, all resuspensions will be subjected to flow cytometric analysis to evaluate erythrocyte NO synthase activity and erythrocyte-mediated NO release.	Drug: Thiopental; Venous blood samples will be taken from the patients included in the study and incubated with thiopental (dose: 100, 250, 500 and 1000µM) after appropriate procedures in the laboratory environment. . After incubation, all resuspensions will be subjected to flow cytometric analysis to evaluate erythrocyte NO synthase activity and erythrocyte-mediated NO release.
Active Comparator: Propofol; Venous blood samples will be taken from the patients included in the study and incubated with propofol (dose: 100, 250, 500 and 1000µM) after appropriate procedures in the laboratory environment. . After incubation, all resuspensions will be subjected to flow cytometric analysis to evaluate erythrocyte NO synthase activity and erythrocyte-mediated NO release.	Drug: Propofol; Venous blood samples will be taken from the patients included in the study and incubated with propofol (dose: 100, 250, 500 and 1000µM) after appropriate procedures in the laboratory environment. . After incubation, all resuspensions will be subjected to flow cytometric analysis to evaluate erythrocyte NO synthase activity and erythrocyte-mediated NO release.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
The effects of thiopental and propofol on erythrocyte NO synthase activity and erythrocyte-mediated NO release.	Blood samples will be taken from healthy human volunteers aged 25-45 years. Measurements will be performed using the fluorescent NO probe 4-amino-5-methylamino-20,70-difluorofluorescein diacetate. Propofol and thiopental will be added to the suspensions at doses of 100, 250, 500 and 1000 µM and incubated for 30 minutes. We will repeate these experiments in the presence of L-NAME, a non-specific nitric oxide synthase inhibitor. The nitrite/nitrate concentration will be measured in the supernatant of the erythrocyte suspensions after centrifugation.Intracellular calcium measurements will also be made during propofol and thiopental experiments. Fluo-4 calcium dye will be added to the medium and flow cytometric measurements will be repeated.	120 days

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
The effects of thiopental and propofol on erythrocyte haemorheology	The effects of thiopental and propofol on erythrocyte haemorheology. Blood samples will be taken from healthy male volunteers and leucocytes will be extracted. The RBC deformability will be measured as an elongation index (EI) for various liquid shear stresses by laser diffraction analysis using an ectacytometer (LORRCA, RR Mechatronics, Hoorn, The Netherlands).RBC aggregation will be assessed using the same echacytometer. Aggregation will be determined by placing 1 ml of blood in the space between the cup and bob. The sample will then be sheared at a speed of 800 1/s for 10 seconds to disperse pre-existing aggregates. After 10 seconds, the shear will be abruptly reduced to zero and the level of laser light reflected from the sample will be digitally recorded for 120 seconds.	120 days

Collaborators and Investigators

• Sponsor: Melike Cengiz
• Investigators: Principal Investigator: Ulku Arslan Yildiz, MD, Akdeniz University School of Medicine, Department of Anesthesiology and Intensive Care, Turkey; Principal Investigator: Pinar Ulker, PhD, Akdeniz University School of Medicine, Department of Physiology; Principal Investigator: Ahmet Yildirim, Akdeniz University School of Medicine, Department of Physiology; Principal Investigator: Ayse Gulbin Arici, Professor, Akdeniz University School of Medicine, Department of Anesthesiology and Reanimation, Turkey; Principal Investigator: Murat Yilmaz, Professor, Akdeniz University School of Medicine, Department of Anesthesiology and Intensive Care, Turkey

Study record dates

Study Major Dates

• Study Start (Actual): March 1, 2024
• Primary Completion (Actual): July 1, 2024
• Study Completion (Actual): July 7, 2024

Study Registration Dates

• First Submitted: March 17, 2024
• First Submitted That Met QC Criteria: June 29, 2024
• First Posted (Actual): July 3, 2024

Study Record Updates

• Last Update Posted (Actual): August 1, 2024
• Last Update Submitted That Met QC Criteria: July 31, 2024
• Last Verified: July 1, 2024

More Information

Terms related to this study

• Keywords: propofol; nitric oxide; erythrocyte; thiopental
• Additional Relevant MeSH Terms: Physiological Effects of Drugs; Neurotransmitter Agents; Molecular Mechanisms of Pharmacological Action; Central Nervous System Depressants; Anesthetics, Intravenous; Anesthetics, General; Anesthetics; Hypnotics and Sedatives; GABA Modulators; GABA Agents; Anticonvulsants; Propofol; Thiopental
• Other Study ID Numbers: Akdeniz U. Faculty

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No