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Chronic hypoxia (10% O 2 ) alters cardiovascular regulation and gene expression in Snapping turtle embryos ( Chelydra serpentina )
Author(s) -
Eme John,
Rhen Turk,
Tate Kevin B,
Gruchalla Kathryn,
Kohl Zachary F,
Slay Christopher E,
Crossley Dane A
Publication year - 2013
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.27.1_supplement.714.15
Subject(s) - endocrinology , hexamethonium , medicine , cholinergic , biology , propranolol , embryo , hypoxia (environmental) , receptor , phentolamine , gene expression , in ovo , acetylcholine , gene , chemistry , microbiology and biotechnology , biochemistry , organic chemistry , oxygen
Reptile embryos are basal amniotic vertebrate developmental models that tolerate severe chronic hypoxia. We measured heart rate (f H ) and arterial blood pressure (P m ) for normoxic (N21) and chronically hypoxic‐incubated (H10; 10% O 2 ) turtle embryos following pharmacological blockade, and we quantified heart tissue mRNA expression for genes using RT‐qPCR. Compared to N21 embryos (controls), H10 embryos were hypotensive and tachycardic, smaller, had relatively larger hearts, and showed reduced intrinsic f H . Unlike other reptile embryos, cholinergic (atropine) and ganglionic receptor blockade (hexamethonium) increased f H , and similar to bird/reptile embryos, adrenoreceptor blockade with propranolol (β) (reduced f H ) and phentolamine (α) (reduced P m ) caused pronounced responses. H10 embryos’ heart tissue had lower mRNA levels for adrenergic receptors (Adrb1, Adra1A, Adra2C) and growth‐related products (Igf1, PdgfB). Cholinergic tone was reduced in H10 embryos, but cholinergic receptor mRNA levels (Chrm2) were unchanged, indicating reduced cardiac receptor gene expression is not responsible for reduced cholinergic tone. Hypoxia likely altered the normal balance between cholinergic receptor and adrenoreceptor function reflected in altered intrinsic f H and adrenoreceptor mRNA levels. This is the first study to link gene expression with morphological and cardioregulatory plasticity in a reptile embryo. NSF CAREER IBN IOS‐0845741 DAC