当前位置： SCI文献检索 > ULTRASONICS期刊下所有文献 > Nitric oxide delivery by ultrasonic cracking: some limitations.

Nitric oxide delivery by ultrasonic cracking: some limitations.

Abstract：

:Nitric oxide (NO) has been implicated in smooth muscle relaxation. Its use has been widespread in cardiology. Due to the effective scavenging of NO by hemoglobin, however, the drug has to be applied locally or in large quantities, to have the effect desired. We propose the use of encapsulated microbubbles that act as a vehicle to carry the gas to a region of interest. By applying a burst of high-amplitude ultrasound, the shell encapsulating the gas can be cracked. Consequently, the gas is released upon which its dissolution and diffusion begins. This process is generally referred to as (ultra)sonic cracking. To test if the quantities of released gas are high enough to allow for NO-delivery in small vessels (ø<200 microm), we analyzed high-speed optical recordings of insonified stiff-shelled microbubbles. These microbubbles were subjected to ultrasonic cracking using 0.5 or 1.7 MHz ultrasound with mechanical index MI>0.6. The mean quantity released from a single microbubble is 1.7 fmol. This is already more than the NO production of a 1mm long vessel with a 50 microm diameter during 100 ms. However, we simulated that the dissolution time of typical released NO microbubbles is equal to the half-life time of NO in whole blood due to scavenging by hemoglobin (1.8 ms), but much smaller than the extravascular half-life time of NO (>90 ms). We conclude that ultrasonic cracking can only be a successful means for nitric oxide delivery, if the gas is released in or near the red blood cell-free plasma next to the endothelium. A complicating factor in the in vivo situation is the variation in blood pressure. Although our simulations and acoustic measurements demonstrate that the dissolution speed of free gas increases with the hydrostatic pressure, the in vitro acoustic amplitudes suggest that the number of released microbubbles decreases at higher hydrostatic pressures. This indicates that ultrasonic cracking mostly occurs during the expansion phase.

journal_name

Ultrasonics

journal_title

Ultrasonics

authors

Postema M,Bouakaz A,ten Cate FJ,Schmitz G,de Jong N,van Wamel A

doi

10.1016/j.ultras.2006.06.003

subject

Has Abstract

pub_date

2006-12-22 00:00:00

pages

e109-13

eissn

0041-624X

issn

1874-9968

pii

S0041-624X(06)00251-4

journal_volume

44 Suppl 1

pub_type

杂志文章

在线工具

Nitric oxide delivery by ultrasonic cracking: some limitations.