System Overview

For more than 100 years pharmacologists and physiologists have been studying cardiac and smooth muscle in tissue baths. WPI’s multi-channel isolated tissue bath system was developed over a period of several years in collaboration with top cardiovascular research scientists. The result is a feature packed, cost-effective system for the in vitro study of vascular and non-vascular smooth muscle. Tissue holders are also available for cardiac muscle and other tissue preparations.

The Myobath-II is available in 2, 4- and 8-channel configurations. Its modular design allows up to four individually mounted baths to be studied simultaneously. Multiple systems can be linked together if more bath set-ups are required. The convenient compact bench-top design of Myobath-II enables the system to be readily located even in tight quarters. WPI’s Custom tailored systems are sold complete with every hook, every hanger and all of the tubing and fittings you need to get right to work. We provide well documented, clear assembly/operation instructions and free telephone support in case you encounter a problem.
 

Tissue Bath
	WPI offers five different tissue baths: 2 mL, 5 mL, 10 mL, 25 mL, and 50 mL. This range is sufficient to cover a broad variety of applications including those involving smaller vessels and tissues from mice or other small animals. Each tissue bath has 6 ports. The baths are jacketed to maintain the temperature of the perfusate in the centre well. The jacket has in inlet and an outlet. A separate inlet with a ceramic frit is used to aerate the perfusate. The frit is designed to produce smaller bubbles that are less prone to strike the tissue or supporting hangers hard enough to cause a perturbation in the force signal. The bath is also provided with a drain port at the bottom of the chamber, an overflow port and a fill port positioned at the top. The overflow insures that perfusate delivered into the bath will not overflow the chamber and contaminate the work surface. It is also critical for automated fill and drain operations using the optional valve bank and valve controller.
Perfusion and Manifolds
Automated Filling and Draining In the standard configuration, both the filling and draining are fed by gravity. Optional automated control of filling and draining is available for four-bath configurations. This option provides efficiency and statistical stability in multi-channel experiments by reducing human interaction. In this configuration, each channel has a solenoid valve control in the filling connection and a solenoid valve control in the draining connection. While filling is still fed by gravity, draining is enhanced with a built-in pump. The solenoid valves are controlled with SVC108 controller, which has 9-pin D-Sub connector for external TTL control signals. The 4-channel auto filling and draining system 472-4AFD includes two 4-channel solenoid valves and one 8-channel solenoid valve controller.
Aeration A 6-channel aeration manifold, designed to regulate the flow of O2/CO2 mixtures, is mounted on the top of the center stainless steel post. Four regulators (needle valves) are used to regulate the flow of O2/CO2 to each individual tissue bath. The remaining two regulators are used to supply O2/CO2 to the buffer reservoir and dissection dish. The buffer reservoir holds warmed, oxygenated buffer solution to fill the tissue baths. The tissue baths and the buffer reservoir are jacketed and require a heating and circulating pump to maintain the desired temperature (e.g., WPI #500787). Drain Manifolds One five-port drain manifold with mounting clamp is supplied with each two channels ordered. Each channel bath connects its drain and overflow ports to the manifold. Five ports are sufficient to accommodate two baths. The fifth port is connected to waste. The advantage of using a manifold is that vacuum may be optionally connected to the waste port, greatly reducing drain times.
Positioners
	Micrometer Positioner/Tensioner The optional Micrometer Transducer Positioner (#47700) can be used to precisely tension tissues and keep track of the exact position or extension of the tissue. The Y axis position can actually be read out from the positioner and fed to a channel of the data system so length and tension can be simultaneously plotted. The user should specify P (for transducer position) or M (micrometer head) in the name.
Classic leadscrew driven positioner/tensioner The Transducer Positioner (#502198) holds any transducer firmly on a stand or rack. The transducer carrier is slotted to accommodate transducers that have their connecting cable exiting from the handle. The device allows the vertical position of the transducer to be easily adjusted with excellent resolution. The compact design keeps the distance between transducer and mounting pole to a minimum. This results in better stability and less vibration pickup. A release button on the positioner allows it to slide freely up or down for quick coarse adjustment. Fine adjustment is achieved by turning the knob on the top. The positioner can be mounted on a pole with a diameter of up to 12.7 mm (1/2-in.). Transducer handles from 7 mm to 11 mm can be mounted on the holder block. Sensor cables can be fed through the open slot in the clamp so that transducers with both ends larger than 11 mm can still be mounted. Total end-to-end travel is 85 mm.
Tissue Holders
	The devices that actually hold tissue for experimentation in a tissue bath are critical to success. They need to be robust, appropriately sized and well thought out in terms of the attachment to the tissue. Since many different sizes and types of tissue can be used in the study of smooth muscle, variety is also critical. WPI offers 10 different application specific tissue support devices. Five types of tissue holders are available for 10-50 mL organ baths and five types of Miniature Tissue Holders are available for smaller tissue preparations. In many applications it is desirable to deliver electrical stimulation to the tissue. WPI offers a series of tissue holders with built in stimulation electrodes. Connection to the stimulation device is accomplished with low mass connectors and wire. These ultimately connect to BNC connectors mounted in the stabilizing par of the frame. Connections to isolators or stimulators can then be made with standard coaxial cables. Glass Hook (G) The glass hook is a universal design utilizing made from a glass rod terminating in an S-shaped glass hook. Stainless steel hooks or fine wire hangers are used to secure the tissue between the glass hook and the force transducer. The glass rod has a diameter 6.5mm and the hook is 2.5 mm away from the side of the glass rod. AS Holder (#47030) The AS holder is used for mounting atrial muscle preparations. This holder is equipped with stimulation electrodes. The tissue is mounted onto the two S-shaped hooks (made from 301/2 gauge needles), The S-hooks measure 2 mm in diameter on both ends with a sharp tip on one end where tissue is pieced. The two point stimulation platinum (Pt) electrodes on the holder are 2.54 mm (0.1in.) apart.
V Holder (#47040) The V holder is used to mount vascular rings. The bottom hook consists of a U-shaped wire. The top hook is an L-shaped wire. The tissue is mounted as shown. The hooks are made from 0.48 mm (0.019 in.) stainless steel wire. The U-shaped hook measures 6.35 mm (0.25 in.) in base.	VS Holder (#47050) V Holder with Stimulation The VS holder uses the same tissue-mounting mechanism as the V holder, but has two 5 mm flexible platinum stimulation electrodes, which can be positioned around the tissue. The stimulation connector and electrodes are designed to be replaceable. The VS holder can only be used in the 25mL or 50mL baths.
B Holder with Stimulation (BS) The B holder is designed for custom-made hooks. The bottom tissue hook is secured with a nylon screw. Stainless steel wire (0.56 mm or 0.022 in.) provided in the startup kit can be used to make the top hook that connects to the strain gauge. Platinum electrodes for point stimulation are identical to those on the AS holder.
Micro Tissue Holders
With the wide use of transgenic mice in studies of this kind, the need for tissue support mechanisms capable of handling the extremely small size of vessels and muscle strips harvested from small animals is paramount. WPI offers five micro-tissue holders for use with micro tissue strips, micro vessels and other tissues where the force measurements are less than 10 g. Micro tissue holders are designed to be used with the 2 mL and 5 mL volume tissue baths and FORT 25 transducer. Micro tissue Holders MH1 and MHS1 are designed for muscle strips as small as 0.5 mm in width and 5 mm in length. The muscle strip is held between two miniature vessel clips with a clamping pressure of 60 grams. These holders are most suitable for measuring isometric force of less than 5-10 grams. MHS1 differs from MH1 only in that it has an in-built stimulation circuit and electrodes. Micro vessel holders MV100, MVS100 and MVS200 require a tissue bath larger than 5 mL and the use of FORT 25 or comparable transducer. These holders are designed for studying tension in vascular rings. When used with the micrometer driven tensioner/positioner they can also be used for measuring the lumen diameter of vessel preparations. The MV100 and MVS100 can be used for micro vessel preparations as small as 500-600 microns (ID). MVS200 is designed for larger vessels (> 2 mm ID). MVS100 and MVS200 feature specially designed spiral stimulation electrodes fabricated from 250-micron diameter platinum wire. The two-and-a-half turns of each spiral electrode span appropriately 4-5 mm. The positions of the spiral electrodes can be adjusted with respect to the tissue placement, a feature that is very useful in controlling stimulus intensity.
Transducers
FORT25 The rigid-lever force transducers transform applied force into proportional voltage. Using balanced strain gauges, FORT transducers produce linear output voltage vs. applied force input with very little deflection. The MYOBATH II system is designed to use together with WPI’s force transducers, including the FORT100 (full scale, 100 g) and FORT25 (full scale, 25 g). These transducers can be directly connected to either the 4-channel Transbridge™ amplifier or the more advanced 8-channel Bridge8 or digital DBA8000 amplifiers. Bridge8 and DBA8000 are the preferred amplifiers for small vessel applications because they provide additional noise filtration (0.03-10Hz). In this way, the noise produced by increased sensitivity of the FORT25 transducer can be significantly attenuated.
FORT10-100 The FORT10-100 is a high sensitivity dual-range research grade force transducer designed to measure forces in the 0.005 to 10 gram and 0 to 100 gram ranges. FORT10-100 exhibits excellent isometric properties. In addition, its unique optical technology makes it resistant to drift and offers intrinsically low noise characteristics. FORT10-100’s on-board amplifiers reduce gain and adjustment requirements on recording amplifiers to which it may be connected.
Amplifiers
	Transbridge All of the transducers above can be directly connected to the 4-channel Transbridge™ amplifier. This basic device offers 4 channels of variable gain transducer conditioning. Each channel has x1 x10 x100 and x1000 gain and offset control. Bandwidth is fixed at 1kHz.
	Bridge 8/IsoDam Rack Bridge8 is the preferred amplifier system for micro vessel applications because it provides additional signal filtration (0.03-10Hz). In this way, the noise produced by more sensitive transducers such as the fort 25 can be significantly attenuated.

MYOBATH can also be supplied with an optional water heater/circulator, gravity-fed buffer pre-warming system, transducers, bridge amplifiers, stimulators, data-acquisition system and chart recorders.

Myobath Configuration

Use the drop down menus below to select your required Myobath setup, and then hit the 'Get Codes' button to obtain the appropriate catalogue codes to request a quotation.