Vascular responses to angiotensins in the toad. Role of the adrenergic system

Pharmacological Research Communications
S S Gamundi

Abstract

The isolated hindlimbs (vasoconstrictor) and the whole toad pressor assays were used to investigate the effects of some angiotensin II (AT II) analogues and the influence of the adrenergic system on the vascular response to AT II in the toad Bufo arenarum. Three of the analogues assayed (Leu8AT II, Sa1, Ala8AT II, Sar1, I1e8AT II) were unable to block the response to AT II, and a fourth, Ala1, Ile8AT II, potentiated it. In the case of Sar1, Ala8AT II (saralasin), this confirms previous negative findings from this laboratory on water and electrolyte transport in toad skin, probably reflecting differences between AT II receptors in mammals and amphibians. This notion is further supported by the fact that desamino AT II, and AT II analogue reported not to produce tachyphylaxis in the guinea-pig ileum, behaves like AT II when injected repeatedly in the isolated hindlimbs. Tyramine was devoid of vascular effects in this preparation. Phentolamine (which blocked the response to norepinephrine) and Ro 4-1284 (an in vitro catecholamine depleting agent) failed to alter the vasoconstrictor action of AT II. An unexpected finding was the inhibiting effect of Ro 4-1284 on the vasoconstrictor response to exogenous norepinephrine.

References


❮ Previous
Next ❯

Citations

Jan 1, 1988·Comparative Biochemistry and Physiology. C, Comparative Pharmacology and Toxicology·M Peral de BrunoA Coviello
Jan 4, 2001·Comparative Biochemistry and Physiology. Part A, Molecular & Integrative Physiology·H Nishimura
Jan 4, 2001·Comparative Biochemistry and Physiology. Part A, Molecular & Integrative Physiology·K Sandberg, H Ji
Dec 17, 2008·Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology·Rodrigo O MarañónMaría Peral de Bruno
Oct 9, 2016·Anatomical Science International·Hiroko Nishimura

❮ Previous
Next ❯

Related Concepts

Related Feeds

Ataxia telangiectasia (MDS)

Ataxia telangiectasia is a rare neurodegenerative diseases caused by defects in the ATM gene, which is involved in DNA damage recognition and repair pathways. Here is the latest research on this autosomal recessive disease.

Related Papers

Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
M Peral de Bruno, A Coviello
Comparative Biochemistry and Physiology. C, Comparative Pharmacology and Toxicology
M Peral de BrunoA Coviello
© 2021 Meta ULC. All rights reserved