Journal: iScience

Article Title: Regulation of interstitial fluid flow in adventitia along vasculature by heartbeat and respiration

doi: 10.1016/j.isci.2024.109407

Figure Lengend Snippet: Regulation of adventitial ISF flow in the venous adventitial pathways by HR and respiration (A) Illustration of the observation on the adventitial ISF flow in the venous adventitial pathways of the femoral vessels. (B) When the HR increased from 150 to 450 bpm, the flow rate of the adventitial ISF also increased (RR 90bpm, I/E 1:1, TV 4.0 mL, n = 1). The fitted curve was calculated based on sigmoid function. (C and C1) When the breath held, like apnea, the adventitial ISF flow rate increased by comparison with that at resting breath. A heavy breath induced a pulsatile flow at the same frequency as the heavy breath. (D, D1, E, and E1) The frequency of the pulsed flow was consistent with the RR in alive or dead rats. (F, F1, G, and G1) The greater the tidal volume, the greater the pulse amplitude of adventitial ISF flow in alive or dead rats. (H, H1, I, and I1) The inspiration and expiration (I/E) ratio (1:1, 2:1, 1:2) determined the descending and ascending branches of the pulse in alive or dead rats. In alive rats, the inflation can decelerate the centripetal adventitial ISF flow. In dead rats, the inflation can cause a centrifugal adventitial ISF flow, while the deflation induced a centripetal adventitial ISF flow. Each group of (C, D, E, F, G, H, and I) was sampled from 6 rats. The solid lines were the mean value and the shaded is the standard deviation of the median velocity of a total 6 rats in each group of (C1, D1, E1, F1, G1, H1, and I1), respectively. The dotted lines (Resp.) are the measured pressure on the surface of the body of a rat by the breathing band sensor, representing the changes of breathing. (J) was from , (K) was , and (L) was . The HR of (J) was around 452bpm, (K) was 220bpm, and (L) was zero. The ventilation parameters of (J), (K), and (L) were all the same, the RR was 30 breaths/min, I/E was 1:1, and tidal volume was 6.0 mL. In either (J) or (K) or (L), the predicted curve (orange) calculated by this cyclical dynamic equation matched the actual measured curves (blue) of the adventitial ISF flow rate very well. Data were represented as mean ± SEM.

Article Snippet: The freshly dead rats referred to the rats that were euthanized by carbon dioxide and used for the experiments within 1 h after the heartbeat and breathing completely stopped for 15 min (detected by ECG and respiration signal monitoring of PowerLab).

Techniques: Comparison, Standard Deviation