Krebs-Ringer bicarbonate solution

The final blood solution is about 1 part blood and 3 parts Krebs-Ringer bicarbonate solution. Ninety-five milliliters of 6% dextran is added to about 550 ml of the fetal blood solution to help prevent fluid from transferring from the fetal to the maternal circulations. The pH of the maternal and fetal solutions are initially in the physiological range... 

The thoracic aorta of male Japanese White rabbits (3-3.5 kg) is cut into helical strips (approximately 4mm wide and 20mm long), and the endothelium is removed by gently rubbing the endothelial surface with cotton pellets. In 1 mL of organ bath containing the modified Krebs-Ringer-bicarbonate solution (120-mM NaCl,... 

Figure 3 Effect of an M2 receptor antagonist (4 iM gaHamine) on the release of acetylcholine from paired cat carotid bodies. Acetylcholine (ACh) released from two carotid bodies (average of two runs) was incubated in Krebs Ringer bicarbonate solution at 37°C for 15 min under normoxic conditions (N solution bubbled with 21%02/5%C02) and then for 15 min tmder hypoxic conditions (H solution bubbled with 4%02/5%C02). Gallamine appears to increase the release of ACh during normoxia and particularly during hypoxia. This pair of carotid bodies released only about 25% of the usual amount released. Presumably the ACh released by the carotid bodies acts on glomus cell autoreceptors to attenuate the further release of ACh. But the block by gallamine inhibits the inhibiting receptor more ACh is released.

Figure 4 In situ recording of neural trafSc in the whole carotid sinus nerve. Cat carotid body is responding to a perfusion of hypoxic Krebs Ringer bicarbonate solution without (open bars) and with (hatched bars) 4 pM AFDX 116, an M2 receptor inhibitor (mean SEM). This neural response could be due to an increase in ACh release because glomus cell M2-inhibiting autoreceptors are inhibited, releasing a greater amount of ACh. Or the postsynaptic M2 receptors (responsible for the slow inhibitory postsynaptic potential) are inhibited, making the postsynaptic sensory afferent neuron more excitable, or both processes.

Hanks balanced salt solution (HBSS) [33], developed in 1949, was again a medium free of any Tris of Hepes, but quite deficient in its HCOb concentration (4.2 mM) and Ga/P molar ratio (1.6) in comparison to those of blood. Tyrode solution, with a Ga/P molar ratio of 4.5 and HGOa" concentration of 12 mM, is a Tris- or Hepes-free basal salt medium [34]. Krebs-Ringer bicarbonate buffer (KRBB) [35], developed In 1932, Is a Tris/Hepes-free solution which raises the HGOa concentration of the Ringer solution [36] from zero to 27 mM, i.e., to that of blood plasma. 

Table2. Composition of Hanks Balanced Salt Solution (HBSS), HBSS-like transport medium (TM) and modified Krebs Bicarbonate Ringer s Solution (KBR).

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