Purine metabolism in response to hypoxic conditions associated with breath-hold diving and exercise in erythrocytes and plasma from bottlenose dolphins (Tursiops truncatus).
In mammalian tissues under hypoxic conditions, ATP degradation results in accumulation of purine metabolites. During exercise, muscle energetic demand increases and oxygen consumption can exceed its supply. During breath-hold diving, oxygen supply is reduced and, although oxygen utilization is regulated by bradycardia (low heart rate) and peripheral vasoconstriction, tissues with low blood flow (ischemia) may become hypoxic. The goal of this study was to evaluate potential differences in the circulating levels of purine metabolism components between diving and exercise in bottlenose dolphins (Tursiops truncatus). Blood samples were taken from captive dolphins following a swimming routine (n=8) and after a 2min dive (n=8). Activity of enzymes involved in purine metabolism (hypoxanthine guanine phosphoribosyl transferase (HGPRT), inosine monophosphate deshydrogenase (IMPDH), xanthine oxidase (XO), purine nucleoside phosphorylase (PNP)), and purine metabolite (hypoxanthine (HX), xanthine (X), uric acid (UA), inosine monophosphate (IMP), inosine, nicotinamide adenine dinucleotide (NAD(+)), adenosine, adenosine monophosphate (AMP), adenosine diphosphate (ADP), ATP, guanosine diphosphate (GDP), guanosine triphosphate (GTP)) concentrations were quantified in erythrocyte and plasma samples. Enzymatic activity and purine metabolite concentrations involved in purine synthesis and degradation, were not significantly different between diving and exercise. Plasma adenosine concentration was higher after diving than exercise (p=0.03); this may be related to dive-induced ischemia. In erythrocytes, HGPRT activity was higher after diving than exercise (p=0.007), suggesting an increased capacity for purine recycling and ATP synthesis from IMP in ischemic tissues of bottlenose dolphins during diving. Purine recycling and physiological adaptations may maintain the ATP concentrations in bottlenose dolphins after diving and exercise.
Centro de Investigaciones Biológicas del Noroeste, S.C., Programa de Planeación Ambiental y Conservación, Instituto Politécnico Nacional 195, Playa Palo Santa Rita Sur, La Paz, Baja California Sur C.P. 23096, México. Electronic address: idelcastillo@pg.cibnor.mx.
Iris
I
Del Castillo Velasco-Martínez
Centro Interdisciplinario de Ciencias Marinas-Instituto Politécnico Nacional, Laboratorio de Ecología de Pinnípedos, Av. Instituto Politécnico Nacional s/n, Playa Palo Santa Rita, La Paz, Baja California Sur C.P. 23096, México. Electronic address: cjhernandez78@gmail.com.
Claudia J
CJ
Hernández-Camacho
Centro de Investigaciones Biológicas del Noroeste, S.C., Programa de Planeación Ambiental y Conservación, Instituto Politécnico Nacional 195, Playa Palo Santa Rita Sur, La Paz, Baja California Sur C.P. 23096, México. Electronic address: lmendez04@cibnor.mx.
Lía C
LC
Méndez-Rodríguez
Centro de Investigaciones Biológicas del Noroeste, S.C., Programa de Planeación Ambiental y Conservación, Instituto Politécnico Nacional 195, Playa Palo Santa Rita Sur, La Paz, Baja California Sur C.P. 23096, México. Electronic address: tzenteno04@cibnor.mx.
Tania
T
Zenteno-Savín
D000818:Animals; D050681:Bottle-Nosed Dolphin / Q000097:blood*; D004242:Diving; D004912:Erythrocytes / Q000201:enzymology / Q000378:metabolism*; D005260:Female; D000860:Hypoxia / Q000097:blood*; D008297:Male; D055442:Metabolome; D010805:Physical Conditioning, Animal; D011687:Purines / Q000378:metabolism*; D012119:Respiration
D011687:Purines; C030985:purine
Bottlenose dolphin; Breath-hold diving; Erythrocytes; Exercise; Hypoxia; Purine metabolism; Purine salvage