Mannitol

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ecolechio
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Mannitol

Hi,

Is anyone familiar with the use of mannitol to reduce or prevent cerebral edema in rat during in vivo optical imaging experiments? I want to use it but the papers I have found focus on use of mannitol with models of ischemia, infarction, etc. - I want to use just a normal adult rat.

Fraser Moss
Fraser Moss's picture
Are you asking what dose to

Are you asking what dose to use? If there is a protective dose in the ischemia models then it should be protective in the normal rat.

1.5 g/kg seemed to be a common dose I found in the literature

ecolechio
ecolechio's picture
Ah great, thanks, I found 2 g

Ah great, thanks, I found 2 g/kg i.v. (in animal anesthetized with 1.5 g/kg i.p. urethane) & 2 g/kg i.p. (in animal anesthetized with alpha-chloralose & isoflurane). I think my advisor prefers the i.v. administration route, but we will be using an initial bolus of ketamine/xylazine and then maintaining anesthesia during the experiment with gaseous isoflurane. Offhand, do you have any thoughts about mixing the mannitol with ketamine?

Fraser Moss
Fraser Moss's picture
This reference might help you

This reference might help you make judgment call

http://www3.interscience.wiley.com/journal/119460382/abstract?CRETRY=1&SRETRY=0

Neurosurgery. 26(2):268-77, 1990 Feb.

Abstract
To evaluate the effect of various anesthetic agents on hyperosmolar blood-brain barrier disruption (BBBD), Sprague-Dawley rats were given pentobarbital (PB), ketamine-xylazine (KX), isoflurane (IF), methoxyflurane (MF), or fentanyl-droperidol (FD) before intracarotid infusion of mannitol or saline. Physiological monitoring showed that the effects of mannitol infusion differed significantly from those of saline infusion and were associated with transient bradycardia, hypotension, metabolic acidosis, and electroencephalographic depression. With PB, KX, or IF anesthesia, we obtained excellent BBBD as evidence by 3+ Evans blue staining of the mannitol-infused cerebral hemisphere. FD anesthesia was associated with tachycardia and MF anesthesia resulted in hypotension; both showed poor Evans blue staining. Radioisotope delivery to the disrupted hemisphere averaged 0.80% of the administered 125I-albumin compared to 0.03% in the contralateral and 0.06% in control (saline-infused) hemispheres. 99mTc-glucoheptonate delivery measured 0.49% of the administered dose after BBBD, 0.03% contralaterally, and 0.05% in control hemispheres. Pharmacological manipulation to normalize the cardiac index in the FD and MF groups resulted in 3+ Evans blue staining and significantly increased delivery of albumin and glucoheptonate. This study suggests that the cardiovascular changes of these specific anesthetic agents are important in obtaining optimal hyperosmolar BBBD.

ecolechio
ecolechio's picture
Thanks very much. We did our

Thanks very much. We did our first experiment with 1.5 g/kg and everything went quite well! :)