High-pressure swivel for infusions into rats

A multipurpose four-channel fluid swivel

This article describes the construction of a functional quadruple fluid swivel with low propensity to leaking and low resistance to rotation. It was obtained through the addition of a fourth channel and some modifications performed on the rotary unit of a triple channel fluid swivel recently described. Those modifications included alterations of the Touhey-Borst adapter (Becton-Dickinson), and the development of a new method of fixation of the rotary tubes to the rotary unit of the swivel using nuts and screws. With those improvements the former swivel was transformed in a still more versatile device that can be used in experimental designs requiring the use of this relatively high number of channels. It can be used, for instance, in simultaneous off-line brain microdialysis of up to four different areas or on-line brain microdialysis in two areas; in push-pull perfusions of two brain regions; in studies determining the neuropharmacokinetics and pharmacodynamics of any compound and combining continuous drug infusion through one channel, double brain microdialysis to describe the distribution characteristics of the drug into the central nervous system as well as to monitor the neurochemical modifications induced by the drug, and continuous plasma sampling to know the plasma pharmacokinetics of the drug. These and several other methods used in neuroscience research can also be combined using the swivel described here.

A new triple-channel swivel for fluid delivery in the range of intracranial (10 nl) and intravenous (100 microliters) self-administration volumes and also suitable for microdialysis

This paper describes a new low-torque, bubble-free and multiple-channel swivel of easy construction. This swivel combined with the use of fused silica capillary tubing to connect syringes and injectors, as we recently proposed, allow the accurate and repeated microinjection of low nanoliter volumes (10 nl) in freely moving rats, as required in the intracranial self-administration paradigm. Microinjections can be simultaneously performed in 3 different brain regions. Relatively large volumes in the 10-100 microliters range can be repeatedly administered, as in intravenous self-administration, using the traditional connections with polyethylene (PE) tubing. This swivel allows the execution of experiments involving in vivo microdialysis in up to 3 different brain areas. The internal channel has a very low dead space (4 microliters) and can be used to withdraw small liquid samples and perform on-line microdialysis in freely moving animals. This versatility makes the present swivel appropriate for sophisticated experimental designs involving combinations of intracranial, intravenous and/or intragastric self-administration with microdialysis.