HEART AND LUNG ADAPTATIONS TO PREGNANCY AND LACTATION IN A CROCIDURINE SHREW

Heart and lung mass, rate of oxygen consumption (V-O2), respiration ra te (fR), tidal volume (VT), and heart rate (fH), were measured at rest and thermoneutrality in the shrew Crocidura russula monacha [(This sh rew is claimed to be Crocidura suaveolens (Catzeflis, F., T. Maddalena , S. Hellwing and P. Vogel (1985). Unexpected findings on the taxonomi c status of East Mediterranean Crocidura russula auct. (Mammalia, Inse ctivora). Zeitschrift fur Saugetierkunde 50: 185-201)] in nullipar (N) , pregnant (P) and lactating (L) females. The heart mass of N females is large (0.86% of body mass) but fH is slow (70% of that expected by mammalian allometry), white lung mass is small (87% of expected) and f R is high (47% above expected). The 31% higher than expected expired v entilation (VE) matches the 25% higher than expected V-O2. In P female s the fH of 560 min(-1) did not change but it increased hi L females t o 620 min(-1). VE did not change in P females but decreased in L femal es from 11.3 ml . min(-1) to 10.1 ml . min(-1). The normal VT decrease d in P and L females from 47.3 mu l to 38.4 mu l and 37.8 mu l respect ively. The lower than expected resting fH of N females may provide suf ficient scope for increased heart work and oxygen supply during exerci se. The large heart may be more efficient. Hyperventilation in N femal es is indicated by the calculated relatively high fractional concentra tion of oxygen in expired air (FE(O2))) and low fractional concentrati on of CO2 in expired air (FE(CO2)) (17.7% and 3.2% respectively), the high oxygen partial pressure in alveolar gas (PA(O2)) and low alveolar CO2 (PA(CO2)), 119 and 34 Torr respectively, which facilitate O-2 tra nsport through the lung air-blood barrier. The elevated VO2 in P and L females is achieved by increased respiratory efficiency from the norm al 15%, to 24% and 29% respectively.