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Willis, John S. Zhao, Zhihong 2011-05-07T14:18:24Z 2011-05-07T14:18:24Z 10000-01-01 1991 It has previously been found that gaining of Na in red cells of guinea pig is faster than in those of ground squirrel during cold storage at 5$\sp\circ$C in vitro and amiloride can partially inhibit the accumulation. Also, amiloride-sensitive Na influx in guinea pig red cells is known to be larger at 20$\sp\circ$C than at 37$\sp\circ$C. In this study, it is shown that amiloride-sensitive Na influx in guinea pig red blood cells can be activated by cytoplasmic H$\sp+$ and it is correlated with cation-dependent H$\sp+$ loss from acidified cells. It is also stimulated by shrinkage and by phorbol ester in the presence of Ca, as is Na-H exchange in other cells. Aside from this apparent Na-H exchange, there are at least one and possibly two other distinct components of amiloride-sensitive Na influx: one is hypertonically induced, with a high sensitivity to amiloride and with low sensitivity to Na; the other appears to represent Na-Mg exchange. Comparison between results at 37$\sp\circ$C and 20$\sp\circ$C shows that amiloride-sensitive Na influx can be activated dramatically by the activators of Na-H exchange at 37$\sp\circ$C, but not at 20$\sp\circ$C. Cell alkalinization can diminish the elevation of amiloride-sensitive Na influx at 20$\sp\circ$C, while depletion of cell magnesium can not. These observations lead to the conclusion that cooling-induced amiloride-sensitive Na influx in guinea pig cells is mainly due to the increased activity of the Na-H exchange mechanism. "By measurement of the stimulation of amiloride-sensitive Na influx by cytoplasmic H$\sp+,$ the affinity of the amiloride-sensitive Na-H exchanger to cytoplasmic H$\sp+$ is found to be higher at 20$\sp\circ$C than at 37$\sp\circ$C. In cells incubated in Na-free medium at 37$\sp\circ$C (""reversed Na gradient""), acidification increased amiloride-sensitive Na efflux, indicating the presence of a cytoplasmic regulatory site for H$\sp+.$ At 20$\sp\circ$C, acidification caused no significant increase, but basification inhibited Na efflux into Na-free medium, indicating higher sensitivity of the regulatory site to cytoplasmic H$\sp+.$ Thus increased activity of the Na-H exchange at reduced temperature is characterized by reduced H$\sp+$ transport but increased affinity of a regulatory site for H$\sp+.$" Made available in DSpace on 2011-05-07T14:18:24Z (GMT). No. of bitstreams: 2 license.txt: 4922 bytes, checksum: 910b249b4beec47e7ab768910c8f966f (MD5) 9211058.pdf: 3877003 bytes, checksum: dc19f6f52727abb523ca9963e5d0039d (MD5) Previous issue date: 1991 Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding (hding2@illinois.edu) on 2011-05-07T15:05:14Z Item is restricted indefinitely. Restriction data tranferred 2014-07-01T11:31:14-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: ETDs are only available to UIUC Users without author permission ETDs are only available to UIUC Users without author permission U of I Only AAI9211058 (UMI)AAI9211058 http://hdl.handle.net/2142/23552 eng Copyright 1991 Zhao, Zhihong Biology, Animal Physiology Biology, Zoology Amiloride-sensitive components of sodium transport in guinea pig red blood cells: A cause of imbalance of sodium ion at low temperature text Biology, Animal Physiology Biology, Zoology Biology, Animal Physiology Biology, Zoology University of Illinois at Urbana-Champaign Dissertation Ph.D.