A 2 × 4 factorial experiment was conducted to determine the bioavailability of zinc (Zn) from amino acids chelated (Zn–Am) and glass embedded Zn (Zn–Gl) as sources for rainbow trout, Oncorhynchus mykiss , fed practical type diets. Two levels of Zn (20 and 40 mg kg−1) were supplemented to the diets using either zinc sulphate (Zn–Sf), zinc methionine (Zn–Mt), Zn–Am or Zn–Gl. Rainbow trout with an average weight of 2 g were fed the experimental diets for 15 weeks. Growth and feed gain ratio (FGR) were not significantly influenced by the dietary Zn content and forms. Alkaline phosphatase (ALP) activity for both levels of Zn–Am was significantly higher than that of Zn–Sf and Zn–Gl at 20 mg supplementation. In another experiment, fish of about 95 g were fed the same experimental diets to determine the absorption of Zn and it was found to be significantly higher from Zn–Am compared with the rest. Retention from Zn–Am at 20 mg was significantly higher than the rest, excluding Zn–Sf. The results suggest that the availability of Zn from Zn–Am might be superior among the sources compared. 相似文献
Three natriuretic peptides with similar structures were isolated from eels and their amino acid sequences determined; atrial
natriuretic peptide (ANP) from atria, ventricular natriuretic peptide (VNP) from ventricles, and C-type natriuretic peptide
(CNP) from brains. All three hormones were circulating in eel blood, and their plasma levels invariably decreased when eels
were transferred from fresh water (FW) to seawater (SW). Eel ANP and VNP inhibited drinking in FW and SW eels. Eel ANP inhibited
water and Na+ absorption by the intestine of SW eels. The potency of these ANP effects was 2–3 orders greater than those of other hormones
which are known to have similar effects. Eel ANP and VNP induced antidiuresis but not antinatriuresis in FW eels. Eel ANP
increased plasma cortisol level in SW eels but not in FW eels. The antidiuretic effect and the stimulation of cortisol secretion
in eels are opposite to the ANP effects reported in mammals. These data suggest that ANP plays a complex role in the eel osmoregulation.
Résumé Trois peptides natriurétiques présentant des structures similaires ont été isolés chez l'anguille et leurs séquences en acides
aminés a été déterminées; le peptide atrial natriurétique (ANP) dans l'atria, le peptide ventriculaire natriurétique (VNP)
dans les ventricules et le peptide natriurétique de type C dans le cerveau. Ces trois hormones sont présents dans le sang
d'anguille et leur niveau plasmatique decroit invariablement quand les anguilles sont transférées d'eau douce en eau de mer.
L'ANP et le VNP d'anguille inhibent l'action de boire chez les anguilles d'eau douce et d'eau de mer. L'ANP d'anguille inhibe
l'absorption d'eau et de Na+ par l'intestin d'anguille en eau de mer. Ces effets de l'ANP sont 2 à 3 fois plus grands que ceux observés avec d'autres
hormones qui sont connues pour avoir des effets similaires. L'ANP et le VNP d'anguille induisent l'antidiurèse mais pas l'antinatriurèse
chez les anguilles d'eau douce. L'ANP d'anguille augmente chez ce poisson les niveaux de cortisol plasmatique en eau de mer
mais pas en eau douce. L'effet antidiurétique et la stimulation de la sécrétion de cortisol chez l'anguille sont contraire
aux effets de l'ANP observés chez les mammifères. Ces résultats suggèrent que l'ANP joue un role complexe dans l'osmorégulation
de l'anguille.
The oral route is presently the preferred route of drug delivery. Poor oral bioavailability results in variable concentrations of drugs in the plasma and variable pharmacological responses, in addition to higher product costs. The unique canine physiology, anatomy and biochemistry makes designing canine dosage forms a challenging exercise. This article reviews the physicochemical, physiological, pharmacokinetic, pharmacological and formulation factors that can influence the drug availability of the oral formulations in dogs in an effort to provide a source of data to aid development of canine drug products with superior bioavailability. 相似文献