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Pharmacological impact on loop gain properties to prevent irregular breathing

100%

Kiwull-Schone H., Teppema L., Wiemann M., Kalhoff H., Kiwull P.

Journal of Physiology and Pharmacology

2008

tom 59

nr 1

Theory predicts respiratory instabilities at elevated system loop gain (G), determined by such factors as ventilatory CO2 sensitivity, set-point PCO2, and metabolic rate. In anesthetized rabbits, the effects on G of carbonic anhydrase (CA) inhibitors and of different sodium/proton exchanger type 3 (NHE3) inhibitors were studied. Acetazolamide significantly reduced G by 42.0 ± 9.3% and methazolamide by 35.0 ± 9.5% (each n = 7, P<0.01). Irrespective of the substance, NHE3 inhibition reduced G by 33.0 ± 7.8% (n = 10, P<0.01) at 35.5 ± 1.6 mmHg PaCO2 (mean ±SE), but not at lower arterial CO2 levels (n=5). Since high baseline PCO2 coincides with elevated brainstem NHE3 mRNA expression, this may also account for a higher risk of sleep apnea (or even occurrence of sudden infant death). Therefore, NHE3 inhibitors may gain similar therapeutic importance in the treatment of irregular breathing as CA inhibitors. Generally, effective treatment should aim at a low system loop gain, by reducing respiratory chemosensitivity, improving blood gases and preventing low metabolic rates.

Carbonic anhydrase activity in the vas deferens of the cotton leafworm - Spodoptera littoralis [Lepidoptera: Noctuidae] controlled by circadian clock

67%

Kotwica J., Ciuk M. A., Joachimiak E., Rowinski S., Cymborowski B., Bebas P.

Journal of Physiology and Pharmacology. Supplement

2006

tom 57

nr 8

107-123

The male reproductive tract of Lepidoptera is an ideal model for the study of the physiological role of peripheral clocks in insects. The latter are significant in the generation and coordination of rhythmic phenomena which facilitate the initial stages of sperm capacitation. This process requires the maintenance of pH in the upper vas deferens (UVD) aided by, among others, H+-ATPase. Our aim was to determine the potential involvement of carbonic anhydrase (CA) in this process, an enzyme tasked with generating protons subsequently utilized by H+-ATPase to acidify the UVD milieu in S. littoralis, during the time when the lumen of this organ is filled with sperm. We attempted to answer the question whether CA activity can be controlled by the biological oscillator present in the male reproductive tract of the cotton leafworm. Using PAGE zymography, the presence of CA was demonstrated in the UVD wall, but not in the luminal fluid nor in the sperm. Using histochemistry, it was shown that CA is active in the UVD epithelium, and that this activity varies throughout the day and is most likely controlled by an endogenous biological clock. Conversely, the application of CA inhibitors, acetazolamide and sodium thiocyanate, in conjunction with an analysis of H+-ATPase activity in the acidification the UVD environment shows that CA most likely does not play a direct role in the regulation of the pH in this organ.

Ograniczanie wyników

1 Journal of Physiology and Pharmacology

1 Journal of Physiology and Pharmacology. Supplement

1 Bebas P.

1 Ciuk M. A.

1 Cymborowski B.

1 Joachimiak E.

1 Kalhoff H.

1 Kiwull P.

1 Kiwull-Schone H.

1 Kotwica J.

1 Rowinski S.

1 Teppema L.

1 Wiemann M.

1 2008

1 2006

Wyniki wyszukiwania

Pharmacological impact on loop gain properties to prevent irregular breathing

Carbonic anhydrase activity in the vas deferens of the cotton leafworm - Spodoptera littoralis [Lepidoptera: Noctuidae] controlled by circadian clock