Key result
Infusion of SQ-14225 depressed drinking and arterial blood pressure in seawater eels, whereas anti-ANG II serum did not, suggesting the renin-angiotensin system plays only a minor role in drinking.
The renin-angiotensin system plays only a minor role in the vigorous drinking observed in seawater eels, and the antidipsogenic and vasodepressor effects of SQ-14225 are not solely due to inhibition of plasma ANG II formation.
Supports RAS-independent drinking control in seawater eels; leaves open non-ANG II targets for SQ-14225 in comparative models.
The role of ANG II, a potent dipsogenic hormone, in copious drinking of seawater eels was examined. SQ-14225 (SQ), an angiotensin-converting enzyme inhibitor, infused intra-arterially at 0.01-1 microgram. kg(-1). min(-1), depressed drinking and arterial blood pressure in a dose-dependent manner. The inhibition was accompanied by a small decrease in plasma ANG II concentration, which became significant at 1 microgram. kg(-1). min(-1). After the infusate was changed back to the vehicle, the depression of drinking and arterial pressure continued for >2 h, although plasma ANG II concentration rebounded above the level before SQ infusion. By contrast, infusion of anti-ANG II serum (0.01-1 microgram. kg(-1). min(-1)) did not suppress drinking and arterial pressure, although plasma ANG II concentration decreased to undetectable levels. Plasma atrial natriuretic peptide and plasma osmolality, which influence drinking rate in eels, did not change during SQ or antiserum infusions. These results suggest that the renin-angiotensin system plays only a minor role in the vigorous drinking observed in seawater eels. The results also suggest that the antidipsogenic and vasodepressor effects of SQ in seawater eels are not due solely to the inhibition of ANG II formation in plasma.
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Takei et al. (2000) studied Seawater-adapted eels. SQ-14225 (SQ) and anti-ANG II serum vs. vehicle was evaluated on Drinking rate and arterial blood pressure. Infusion of SQ-14225 depressed drinking and arterial blood pressure in seawater eels, whereas anti-ANG II serum did not, suggesting the renin-angiotensin system plays only a minor role in drinking.
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