Mechanical and vasomotor properties of piglet isolated middle cerebral artery

Abstract

Piglets are often used as experimental models for studying cerebrovascular responses in newborn infants. However, the mechanical characteristics of piglets’ middle cerebral arteries (MCA) are not well characterized. Additionally, the vessels’ response to dopamine, the most commonly used vasopressor in newborns, is not characterized in piglets’ MCA. Finally, the influence of preterm birth on the dopamine response is not known. The aim of this current was to compare by wire myography the active and passive mechanical characteristics and dopamine concentration–response relations of MCAs isolated from preterm and term newborn piglets. Second‐order branches of the MCA with a diameter <400 μm were chosen for study. The active and passive mechanical properties were comparable between vessels from six preterm (90% gestation, nsegments = 11) and nine term (nsegments = 22) newborn piglets. The response to increasing concentrations of dopamine was biphasic, starting with vasodilation in the 1 nmol/L–0.3 μmol/L concentration range followed by vasoconstriction at higher concentrations. The response was very similar between the two groups. In conclusion, the mechanical properties of the MCA as well as the response to dopamine were comparable between term and 90% gestation preterm piglets.

Association between dopamine and cerebral autoregulation in preterm neonates

“…Cerebral artery myogenic tone may also be biphasic with vasodilation at lower dopamine concentrations and vasoconstriction noted at higher concentrations. 25 In addition, we speculate that the severity of illness when requiring high doses of dopamine leads to the addition of other medications, such as additional inotropes and hydrocortisone, fluid resuscitation, and blood products exposure, all of which may affect the autoregulatory threshold. In this cohort, 11 subjects were treated with these additional interventions; however, the relatively small number of infants and multiple interventions limits our ability to analyze the specific effects of interventions such as steroids on cerebral autoregulation in this study.…”

Cerebral microcirculation mapped by echo particle tracking velocimetry quantifies the intracranial pressure and detects ischemia

“…Included are a macro blood vessel (region #5), the thalamus (region #1), and the cortex divided into three sub-regions (regions #2–4) based on their locations relative to macro-vessels. For thalamus and cortex, taking advantage of the high spatial resolution features of the vascular map, the areas occupied by macro-vessels with in-plane width more than 400 μm (corresponding to the second-order branches of the middle cerebral artery in piglets 46 ) are excluded (Fig. 1c , maximum width is ~390 μm), and the analyses are focused on the micro-vessels.…”