αCGRP-Induced Changes in Cerebral and Systemic Circulation; A TCD Study

Area of Science:

• Cardiovascular Physiology
• Neurovascular Regulation
• Pharmacology

Background:

• Calcitonin gene-related peptide (CGRP) is known to cause cerebral vasodilation when applied perivascularly.
• The effects of intravenous alpha CGRP (αCGRP) on cerebral and systemic hemodynamics remain largely uncharacterized.

Purpose of the Study:

• To investigate the hemodynamic effects of a continuous intravenous infusion of αCGRP in healthy human subjects.
• To assess changes in cerebral blood flow velocity and systemic parameters during αCGRP administration.

Main Methods:

• Twenty healthy volunteers received an intravenous infusion of αCGRP at 1.5 mcg/min for 20 minutes.
• Transcranial Doppler (TCD) was used to measure mean arterial velocity in the middle cerebral artery (vm MCA) and posterior cerebral artery (vm PCA).
• Mean arterial pressure (MAP), heart rate (HR), and end-tidal CO2 (Et-CO2) were also monitored.

Main Results:

• αCGRP infusion led to significant decreases in vm MCA (p < 0.001), vm PCA (p < 0.001), MAP (p < 0.001), and Et-CO2 (p = 0.030).
• Heart rate significantly increased during the infusion (p < 0.001).
• A positive correlation was observed between Et-CO2 and vm MCA (p = 0.001) and vm PCA (p = 0.043).

Conclusions:

• Intravenous αCGRP administration induces significant changes in both cerebral and systemic circulation in healthy volunteers.
• The findings suggest αCGRP may cause vasodilation in the MCA and PCA, potentially leading to a compensatory decrease in Et-CO2.
• Further research is warranted to elucidate the precise mechanisms and clinical implications of these hemodynamic alterations.