Premium
Vasodilatation by carbon dioxide and sodium nitroglycerin reduces compliance of the cerebral arteries in humans
Author(s) -
Moir M. Erin,
Vermeulen Tyler D.,
Smith Sydney O.,
Woehrle Emilie,
Matushewski Brad J.,
Zamir Mair,
Shoemaker J. Kevin
Publication year - 2021
Publication title -
experimental physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0958-0670
DOI - 10.1113/ep089533
Subject(s) - hypercapnia , compliance (psychology) , medicine , vasodilation , vascular resistance , anesthesia , cerebral perfusion pressure , transcranial doppler , middle cerebral artery , cardiology , cerebral autoregulation , cerebral blood flow , cerebral arteries , cerebral circulation , blood pressure , hemodynamics , ischemia , respiratory system , autoregulation , psychology , social psychology
New FindingsWhat is the central question of this study? Vascular compliance importantly contributes to the regulation of cerebral perfusion and complex mechanisms are known to influence compliance of a vascular bed: while vasodilatation mediates changes in vascular resistance, does it also affect compliance, particularly in the cerebral vasculature?What is the main finding and its importance? Cerebral vasodilatation, elicited by hypercapnia and sodium nitroglycerin administration, reduced cerebrovascular compliance by approximately 26% from baseline. This study provides new insight into mechanisms mediating cerebrovascular compliance.Abstract Changes in vascular resistance and vascular compliance contribute to the regulation of cerebral perfusion. While changes in vascular resistance are known to be mediated by vasodilatation, the mechanisms contributing to changes in vascular compliance are complex. In particular, whether vasodilatation affects compliance of the vasculature within the cranium remains unknown. Therefore, the present study examined the impact of two vasodilatation pathways on cerebrovascular compliance in humans. Fifteen young, healthy adults (26 ± 5 years, seven females) completed two protocols: (i) sublingual sodium nitroglycerin (SNG; 0.4 mg) and (ii) hypercapnia (5–6% carbon dioxide gas mixture for 4 min). Blood pressure waveforms (finger photoplethysmography) and middle cerebral artery blood velocity waveforms (transcranial Doppler ultrasound) were input into a modified Windkessel model and an index of cerebrovascular compliance (Ci) was calculated. During the SNG protocol, Ci decreased 24 ± 17% from baseline ((5.0 ± 2.3) × 10 –4 cm s –1 mmHg –1 ) to minute 10 ((3.6 ± 1.2) × 10 –4 cm s –1 mmHg –1 ; P = 0.009). During the hypercapnia protocol, Ci decreased 28 ± 9% from baseline ((4.4 ± 1.9) × 10 –4 cm s –1 mmHg –1 ) to minute 4 ((3.1 ± 1.4) × 10 –4 cm s –1 mmHg –1 ; P < 0.001). Cerebral vasodilatory stimuli induced by nitric oxide and carbon dioxide mechanisms reduced compliance of the cerebral vascular bed by approximately 26% from supine baseline values.