FETAL HEART MITOCHONDRIAL RESPIRATORY ACTIVITY FOLLOWING β-RECEPTOR BLOCKADE IN UTERO DURING HYPOXIA

Autor: Rey-In Lin, Juan G. Alvarez, L Craig Wagerle, Geoffrey Rose, Maria Delivoria-Papadopoulos, Linda M Sacks
Rok vydání: 1984
Předmět:
Zdroj: Pediatric Research. 18:126A-126A
ISSN: 1530-0447
0031-3998
DOI: 10.1203/00006450-198404001-00200
Popis: The present study investigates the contribution of endogenous β - receptor stimulation mediated through hypoxia to the adaptive response of MITO to hypoxia in fetal guinea pig hearts. Twenty pregnant guinea pigs were divided in 4 groups: Gr C (control), Gr H (hypoxia, 7-10% O2 for 1 hr), Gr P (propranolol HCI, 1.0 mg/kg, I.V.), Gr PH (propranolol + hypoxia). States 3 and 4 MITO respiratory rates (RR) (nmol O2/min/nmol a+a3) were assayed with glutamate-malate (GM), succinate (SU), and tetramethyl-p-phenylene-diamene HCl/ascorbate (TMDP). State 3 and 4 RR's in Gr C fetal hearts were 89.9 and 13.7 (GM), 81.3 and 25.5 (SU), 170 and 125 (TMPD), respectively. The Ca++ uptake (murexide method) was 51.3 nmol Ca++/min/nmol a+a3 in this group. Fetal hearts in Gr H had increased State 3 RR and Ca++ uptake (significantly to 159.9 nmol/min/nmol a+a3) but not State 4 RR. Gr P showed increases in States 3 and 4 RR over Gr C by 33% and 28% (GM), 57% and 37% (SU), 26% and 0% (TMPD) respectively. In similar studies in newborn pigs, Gr P State 3 (GM) increased to 137.7 from 70.4 (Gr C). In Gr PH, hypoxia had a less significant effect on the MITO RR and Ca++ uptake compared to Gr H and Gr P (107.7, GM; 147.2, SU; 245.2, TMPD for State 3 and 7.36, GM; 18.8, SU; 122.6, TMPD for State 4 and Ca++ uptake was 144.5). Propranolol increases MITO respiratory activity presumably through sympathomimetic actions. Since effects of propranolol and hypoxia are different (propranolol increased States 3 and 4 while hypoxia increased only State 3), it would appear that the adaptive response to hypoxia is not mediated through β-receptor activation.
Databáze: OpenAIRE
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