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No Hemoglobin but NO: the icefish(Chionodraco hamatus)heart as a paradigm.
No full textThe role of nitric oxide (NO) in cardio-vascular homeostasis is now known to include allosteric redox modulation of cell respiration. An interesting animal for the study of this wide-ranging influence of NO is the cold-adapted Antarctic icefish Chionodraco hamatus, which is characterised by evolutionary loss of hemoglobin and multiple cardio-circulatory and subcellular compensations for efficient oxygen delivery. Using an isolated, perfused working heart preparation of C. hamatus, we show that both endogenous (L-arginine) and exogenous (SIN-1 in presence of SOD) NO-donors as well as the guanylate cyclase (GC) donor 8Br-cGMP elicit positive inotropism, while both nitric oxide synthase (NOS) and sGC inhibitors, i.e. L-NIO and ODQ, respectively, induce significant negative inotropic effects. These results therefore demonstrate that under basal working conditions the icefish heart is under the tonic influence of a NO-cGMP-mediated positive inotropism. We also show that the working heart, which has intracardiac NOS (shown by NADPH-diaphorase activity and immunolocalization), can produce and release NO, as measured by nitrite appearance in the cardiac effluent. These results indicate the presence of a functional NOS system in the icefish heart, possibly serving a paracrine/autocrine regulatory role
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Antagonistic actions of prostaglandins E2 and F2 alpha on the isolated lungs of the frog, Rana esculenta L.
Full text link1. Isolated lungs of the frog, Rana esculenta L., when incubated in amphibian Ringer solution for 30 min, produced a prostaglandin E2-like substance (27.1 ± 3.8 ng/g w.w.), as determined by bioassay on the isolated rat stomach strip. 2. The release of PGE2-like substance from skin, heart and bowel is also reported. 3. The activity of synthetic prostaglandins E2 (PGE2) and F2alpha (PGF2alpha) on the muscular contractility of frog isolated lungs was investigated: PGE2 and PGF2alpha relaxed and contracted respectively in a dose-dependent manner this preparation, a result similar to that obtained in mammals
Divergence in vascular actions of prostacyclin during vertebrate evolution
Full text linkProstacyclin (PGI2) generation by teleost and elasmobranch fish vascular wall was detected, as 6‐keto‐PGF1α‐like immunoreactivity, in the incubation medium of ventral aorta rings from Anguilla anguilla, Conger conger and Scyliorhinus stellaris. The average yields after 15 min incubation were the following (ng of 6‐keto‐PGF1α‐like/g of wet tissue): A. anguilla =116.8 ±30; C. conger = 7.50; S. stellaris = 58.0 ± 10.
Accordingly, the vascular responses to synthetic PGI2 were examined on the isolated and saline‐perfused head of four teleost (A. anguilla, C. conger, S corpaena porcus and Solea solea) and two elasmobranch (S. stellaris and Torpedo marmorata) species. In teleosts, PGI2 gave a dose‐related increase in overall gill vascular resistance, unaffected by indomethacin, phenoxybenzamine and phentolamine pretreatment or by previous decerebration of the animal. Conversely, in elasmobranchs PGI2 elicited a diphasic response, characterized by a transient, not dose‐related constriction, followed by a longer lasting and dosedependent dilation.
The effects of PGI2 on isolated branchial arch (in A. anguilla, C. conger and S. stellaris) and ventral aorta strips (in C. conger and S. stellaris) were also examined. Both preparations shared the same responsivity of the head in toto, confirming the divergence observed in this respect between teleosts and elasmobranchs. The reactivity of teleost branchial vessels to this autacoid appears to be unique among the other vertebrates examined thus far
On the heterogeneity of the fish heart ventricle: II. A functional overview. Boll Soc Ital Biol Sper. 1977 Nov 30;53(22):1996-9.
No full textPerformance of the isolated rainbow trout heart perfused under self-controlled coronary pressure conditions: effects of high and low oxygen tension, arachidonic acid and indomethacin
No full textComparative study of the arterial and lacunary systems of the ventricular myocardium of elasmobranch and teleost fishes.
No full textOn the heterogeneity of the fish heart ventricle: II. A functional overview. Boll Soc Ital Biol Sper. 1977 Nov 30;53(22):1996-9.
No full textNew biological aspects of Chromogranin A-derived peptides: Focus on vasostatins
No full textChromogranin A (CgA), one component of the granin family, represents the major soluble protein co-stored and co-released with catecholamines, within chromaffin cells secretory granules. It is considered a diagnostic and prognostic marker of several diseases, including a variety of tumours and cardiac heart failure. It also represents a precursor of biologically active fragments, generated after proteolytic cleavage at the level of the multiple pairs of dibasic sites which enrich its sequence
Comparative study of the arterial and lacunary systems of the ventricular myocardium of elasmobranch and teleost fishes.
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