[Histonet] RE: perfusion debate

[Charles Scouten]

It depends on where the bottleneck is.  If the cardiovascular system is the main source of resistance, it will feel all 300 mm Hg.  If the tubing or needle is small, it will absorb the pressure drop, and the cardiovasucalar system will get much less than the gauge pressure the perfusion bottle was pumped up to.  A mouse has much more cardiovascular resistance than a rat.  A pig would have much much less.

The largest suitable needle and tubing (1/4" ID tubing), would insure that the animal was the main source of resistance if the flow was small (mouse or even rat), but larger animals would require larger tubing and needle.  

Remember, the hanging bag pressure needs to be about 13 feet above the animal to provide a pressure that will disrupt the blood brain barrier.  The correct flow rate to use depends greatly on animal size and condition.  The correct pressure is constant, but needs to be higher than traditional gravity flow can typically provide.  So it is better to control pressure directly, rather than flow rate.  

For an inexpensive means of implementing this strategy, and getting no shrink perfusions, go to www.myneurolab.com, click products, click sacrifice instruments under the Histology header, click Perfusion One.


Cordially,

Charles W.  Scouten, Ph.D. 
myNeuroLab.com
5918 Evergreen Blvd. 
St. Louis, MO 63134 
Ph: 314 522 0300  
FAX  314 522 0377 
cwscouten <@t> myneurolab.com 
www.myneurolab.com 

 -----Original Message-----
From: 	histonet-bounces <@t> lists.utsouthwestern.edu [mailto:histonet-bounces <@t> lists.utsouthwestern.edu]  On Behalf Of Tamara Howard
Sent:	Monday, April 05, 2004 12:57 PM
To:	HistoNet
Subject:	[Histonet] RE: perfusion debate

As far as the relationship of mm Hg to ml/min with a perfusion pump -
aren't the innner diameter and stiffness of the tubing (and the i.d. of
the cannula) going to influence the final pressure, too? I don't think
adjusting final pump speed alone is going to accurately duplicate the
"hanging bag" pressure. Can you check the literature and see what other
groups have reported and work from there?

|--------------------------------------------------|
 Tamara Howard
 Department of Cell Biology and Physiology
 University of New Mexico - Health Sciences Center
 Albuquerque, NM 87131
 thoward <@t> unm.edu
|--------------------------------------------------|


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