Diving mammals may enhance dive duration by injecting extra erythrocytes into the circulation by spleen contraction. This mechanism may also be important for apneic duration in humans. We studied the speed and magnitude of spleen volume changes evoked by serial apneas, and the associated changes in hematocrit (Hct) and hemoglobin (Hb) concentration, diving response and apneic duration. Three maximal apneas separated by 2 min rest elicited spleen contraction in all ten subjects, by a mean of 49 (27) ml (18%; P<0.001). During the same period, Hct and Hb rose by 2.2 and 2.4% respectively (P<0.01 and P<0.001), and apneic duration rose by 20 s (22% P<0.05). The mean heart rate reduction of the diving response was 15%, which remained the same throughout the apnea series. While the diving response was completely reversed between the apneas, spleen size was not recovered until 8–9 min after the final apnea corresponding with recovery of Hct and Hb. Thus, although the spleen contraction may be associated with the cardiovascular diving response, it is likely to be triggered by different mechanisms, and it may remain activated between dives spaced by short pauses. The two adjustments may provide a fast, quickly reversed, and a slow, but long-lasting, way of shifting to a diving mode in humans.
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We want to express our sincere gratitude to all subjects who participated in this study, to Staffan Pilström for developing the formula for spleen volume calculation, and to Marie Andersson for help with blood sampling and analysis. This study was supported by The Swedish National Center for Research in Sports, and research grants from Landstinget Västernorrland and Sundsvalls Sjukhus.
Andersson J, Schagatay E (1998) Arterial oxygen desaturation during apnea in humans. Undersea Hyperb Med 25:21–25PubMedGoogle Scholar
Espersen K, Frandsen H, Lorentzen T, Kanstrup I-L, Christensen NJ (2001) The human spleen as an erythrocyte reservoir in diving-related interventions. J Appl Physiol 92:2071–2079Google Scholar
Hentsch U, Ulmer HV (1984) Trainability of underwater breath-holding time. Int J Sports Med 5:343–347PubMedGoogle Scholar
Hurford WE, Hong SK, Park YS, Ahn DW, Shiraki K, Mohri M, Zapol WM (1990) Splenic contraction during breath-hold diving in the Korean ama. J Appl Physiol 69:932–936PubMedGoogle Scholar
Hurford WE, Hochachka PW, Schneider RC, Guyton GP, Stanek KS, Zapol DG, Liggins GC, Zapol WM (1996) Splenic contraction, catecholamine release, and blood volume redistribution during diving in the Weddell seal. J Appl Physiol 80:298–306PubMedGoogle Scholar
Hurwitz BE, Furedy JJ (1986) The human dive reflex: an experimental, topographical, and physiological analysis. Physiol Behav 36:287–294CrossRefPubMedGoogle Scholar
Israel S (1957) Neue Geschtspunkte zum Atemanhaltenversuch in Klinik und sportärztlicher Praxis. Z Gesamte Exp Med 12:1048–1052PubMedGoogle Scholar
Koga T (1979) Correlation between sectional area of the spleen by ultrasonic tomography and actual volume of the removed spleen. J Clin Ultrasound 7:119–120PubMedGoogle Scholar
Laub M, Hvid-Jacobsen K, Hovind P, Kanstrup IL, Christensen NJ, Nielsen SL (1993) Spleen emptying and venous hematocrit in humans during exercise. J Appl Physiol 74:1024–1026PubMedGoogle Scholar
Lin YC, Lally DA, Moore TO, Hong SK (1974) Physiological and conventional breath-hold breaking points. J Appl Physiol 37:291–296PubMedGoogle Scholar
Lundvall J, Bjerkhoel P (1994) Failure of hemoconcentration during standing to reveal plasma volume decline induced in the erect posture. J Appl Physiol 77:2155–2162PubMedGoogle Scholar
Persson SG, Ekman L, Lydin G, Tufvesson G (1973) Circulatory effects of splenectomy in the horse. I. Effect on red-cell distribution and variability of haematocrit in the peripheral blood. Zentralbl Veterinarmed A 20:441–455PubMedGoogle Scholar
Qvist J, Hill RD, Schneider RC, Falke KJ, Liggins GC, Guppy M, Elliot RL, Hochachka PW, Zapol WM (1986) Hemoglobin concentrations and blood-gas tensions of free-diving Weddell seals. J Appl Physiol 61:1560–1569PubMedGoogle Scholar
Schagatay E (1996) The human diving response—effects of temperature and training. Thesis, Lund University, Lund, SwedenGoogle Scholar
Schagatay E, van Kampen M, Andersson J (1999) Effects of repeated apneas on apneic time and diving response in non-divers. Undersea Hyperb Med 26:143–149PubMedGoogle Scholar
Schagatay E, Andersson J, Hallén M, Pålsson B (2001a). Physiological and genomic consequenses of intermittent hypoxia. Selected contribution: role of spleen emptying in prolonging apneas in humans. J Appl Physiol 90:1623–1629PubMedGoogle Scholar
Schagatay E, Andersson J, Nielsen B (2001b) Does facial chilling augment the hematocrit increase seen at human apneic diving? In: International thermal physiology symposium, Wollongong, Australia, 2–6 September 2001, vol 32[Suppl 1], p 138Google Scholar