In vitro development of equine oocytes from preserved ovaries after intracytoplasmic sperm injection

In this study, we evaluated the meiotic competence of equine oocytes from ovaries preserved for one day. We also investigated fertilization, cleavage rate, developmental competence and freezability of equine embryos after intracytoplasmic sperm injection (ICSI). After collection from ovaries, the oocytes were classified into two groups comprised of those having compact cumulus layers (Cp) or those having expanded cumulus layers (Ex). Oocytes with a first polar body were subjected to fertilization by ICSI using frozen-thawed stallion spermatozoa and were then cultured in CR1aa medium. The rates of metaphase II-stage oocytes, normal fertilization and cleavage were not significantly different between the two oocyte categories (38.5, 70.0 and 48.7% for CP and 43.5, 60.0 and 58.8% for Ex, respectively). However, the blastocyst development rate of Ex was significantly (P<0.05) higher than that of Cp (25.5 vs. 7.7%). Three Cp-derived and 12 Ex-derived early blastocysts were cryopreserved using the slow cooling protocol, and all of them developed to hatching blastocysts after thawing. These results suggest that equine oocytes fertilized by ICSI can develop to the preimplantation stage in culture conditions similar to those used in the bovine. Furthermore, the Ex oocytes had higher developmental competence than the Cp oocytes, and the in vitro-produced blastocysts had high viability after freezing and thawing.

117 EFFECT OF STEPWISE DILUTION ON THE VIABILITY OF FROZEN - THAWED BOVINE OOCYTES MATURED IN VITRO

The purpose of this study was to evaluate the effect of stepwise dilution on the viability of frozen–thawed bovine oocytes matured in vitro. Oocytes matured in vitro were denuded and equilibrated in modified TCM-199 (m199: 11 mmol L-1 HEPES, 9 mmol L-1 Na-HEPES, 5 mmol L-1 NaHCO3, 20% (v/v) calf serum) supplemented with 10% (v/v) glycerol for 15 min at room temperature (RT). Then they were exposed to m199 with 10% glycerol and 0.25 mol L-1 sucrose and loaded into 0.25-mL plastic straws. The straws were sealed and seeded at -6�C, cooled at the rate of 0.33�C min-1 to -25�C, and plunged into LN2. For thawing, the straws were first held in air at RT for 10 s, followed by immersion in 30�C water for 10 s. In the first experiment, frozen-thawed oocytes were subjected to cryoprotectants in 5 different manners of dilution. In the non-step dilution, the oocytes (n = 60) were put into m199 for 5 min. In the single-step dilution, the oocytes (n = 37) were transferred to 0.25 mol L-1 sucrose in m199 for 5 min. In the two-step dilution, the oocytes (n = 56) were transferred to 0.5 and then 0.25 mol L-1 sucrose in m199 for 5 and 5 min, respectively. In the three-step dilution, the oocytes (n = 57) were transferred to 0.75, 0.5, and 0.25 mol L-1 sucrose in m199 for 1, 5, and 5 min, respectively. In the four-step dilution, the oocytes (n = 52) were transferred to 1.0, 0.75, 0.5, and 0.25 mol L-1 sucrose in m199 for 1, 1, 5, and 5 min, respectively. After dilution, all of the oocytes were washed twice in TCM-199 supplemented with 5% fetal bovine serum for 5 min and cultured for 1 h to assess the morphology. The rate of morphological normal oocytes in the four-step dilution (94.2%) was significantly (P &lt; 0.05) higher than that in other groups (non-, single-, two-, and three-step dilution: 61.7%, 73.0%, 78.6%, and 77.2%). In the second experiment, non-frozen (control, n = 170) and frozen–thawed oocytes (n = 145) with four-step dilution were fertilized and cultured in vitro (Kuwayama 1992 J. Reprod. Fert. 96, 187–193). To assess fertilization, some of the oocytes were fixed at 10 h after insemination. Cleavage and blastocyst rates were determined on Day 2 and Day 8 after fertilization (Day 0), respectively. There was no difference (P &gt; 0.05) between control and frozen–thawed oocytes in the fertilization rate (88.0% vs. 93.1%). Some of the frozen–thawed oocytes cleaved and developed to blastocysts (44.0% and 11.2%), although the rates were significantly (P &lt; 0.01) lower than those in control (71.7% and 35.0%). These results indicate that stepwise dilution of frozen–thawed oocytes improves the recovery of oocytes with normal morphology, and that the oocytes maintain the abilities to be fertilized and develop to blastocysts.

24 EFFECT OF TREATMENT WITH TRICHOSTATIN A ON IN VITRO DEVELOPMENT OF BOVINE NUCLEAR-TRANSFERRED EMBRYOS

It has been reported that 5 or 50 nM trichostatin A (TSA) treatment after somatic cell nuclear transfer (NT) improves the success rate of mouse cloning (Kishigami et al. 2006 Biochem. Biophys. Res. Commun. 340, 183–189). In this study, we examined the effect of TSA treatment on the in vitro development of bovine NT embryos. As donor cells for NT, bovine fibroblast cells of passages 3 to 5 were used following culture in serum-starved medium for 5 to 7 days. Oocytes were enucleated after in vitro maturation in TCM-199 supplemented with 10% fetal bovine serum. Enucleated MII oocytes were fused with fibroblast cells by a DC pulse of 25 V/150 µm for 10 µs in Zimmerman mammalian cell fusion medium. Fused oocytes were activated by 10 µM calcium ionophore for 5 min, followed by incubation with 2.5 µg mL−1 cytochalasin D, 10 µg mL−1 cycloheximide, and 5 or 50 nM TSA for 1 h, and then cycloheximide and 5 or 50 nM TSA for 4 h. After chemical activation, NT embryos were cultured in IVD-101 (Research Institute of Functional Peptide Co., Ltd., Yamagata, Japan) with 5 or 50 nM TSA for 10 h and subsequently cultured in IVD-101 without TSA. Control NT embryos were cultured in the same medium without TSA after fusion. After in vitro culture for 8 days, blastocyst formation and cell numbers of blastocysts were examined. The fusion rate of enucleated oocytes with fibroblast cells was 81% (199/247). In vitro development of NT embryos is summarized in Table 1. There were no differences in the cleavage rate and development rate to the blastocyst stage of NT embryos among control, and 5 and 50 nM TSA treatments. The cell number of 50 nM TSA-treated NT embryos at the blastocyst stage was higher than that of control NT embryos without TSA treatment. In conclusion, 50 nM TSA treatment for 15 h after activation did not affect the in vitro developmental competence, but increased total cell number in bovine NT embryos. These results suggest that TSA treatment may improve the quality of blastocysts in bovine NT. Table 1. Effects of TSA treatment on in vitro development of NT embryos derived from fibroblast cells

203 PRODUCTION OF ANDROGENETIC SHEEP BLASTOCYSTS

The androgenetic embryo is a useful model for investigating the contribution of the paternal genome (e.g. genomic imprinting) to embryonic development. Few works on androgenetic embryo production in domestic animals exist. In this study, we compared the developmental ability of diploid, haploid, and triploid androgenetic sheep embryos. In vitro-matured metaphase II oocytes were enucleated in HEPES-buffered TCM-199 with cytochalasin B (7.5 µg mL−1) and Hoechst 33342 (5 µg mL−1) under UV light using a Narishighe Micromanipulator fitted to an inverted Nikon microscope. Enucleated oocytes were fertilized in vitro with a high sperm concentration (2.5 × 107 sperm mL−1). Fifteen hours after in vitro fertilization (IVF), embryos were centrifuged (12 000g for 10 min) to visualize the pronuclei; the number of pronuclei were scored under the inverted microscope. In Experiment 1, IVF (control), haploid (1 pronucleus), diploid (2 pronuclei), and triploid (3 pronuclei) embryos were cultured in SOFaa medium with BSA, according to the protocol in our laboratory (Ptak et al. 2002 Biol. Reprod. 67, 1719–1725). In Experiment 2, we performed pronuclear transfer to produce diploid embryos. A single pronucleus was aspirated with a bevelled pipette from haploid (haploid + haploid) or diploid (diploid + haploid) embryos and transferred into the perivitelline space of another haploid embryo. The reconstructed zygotes were electrofused in 0.27 M mannitol solution with 50 µM CaCl2 and 100 µM MgCl2 by a single DC pulse (0.8 kV cm−1 for 80 µs). As a control group for Experiment 2, IVF embryos (pronuclear stage) were centrifuged, followed by the aspiration of a small volume of cytoplasm, and fused under the same condition of diploidization. In Experiment 1, there was no significant difference in cleavage rate (91% to 98%), but there was a significant difference on blastocyst development between IVF and androgenetic embryos (IVF: 43% (26/60); haploid: 0% (0/37); diploid: 1% (1/73); and triploid: 2% (1/48)). In Experiment 2, there was no significant difference in cleavage rate (94% to 100%). However, there was a significant difference on blastocyst development (Control: 42%; haploid + diploid: 19%; and haploid + haploid: 3%; Table 1). Our results suggest that sheep androgenetic embryos show poor developmental ability compared with IVF embryos. Interestingly, diploid androgenetic embryos produced by IVF displayed very poor development; however, such poor development was rescued, for unknown reasons, by pronuclear transfer. Ongoing experiments will provide new insight into this previously uncharacterized phenomenon. In conclusion, pronuclear transfer was an effective method for producing sheep androgenetic blastocysts in vitro. Table 1.Development of androgenetic embryos after pronuclear transfer

202 INNER CELL MASS EXCHANGE IN SHEEP EMBRYOS

The presence of a developmental axis in the mammalian oocyte/embryo is still a controversial issue (Plusa 2005 Nature 17, 391–395). However, pre-established or not, mammalian blastocysts display a clear asymmetry with distinct embryonic and abembryonic poles. The present emphasis on ‘mosaic’ development in mammalian embryos is in contrast with classical embryological work, aimed at cell lineage analysis, where manipulation procedures severely perturbed the natural blastocyst asymmetry (Gardner 2001 RBM Online 4, 46–51). However, all of the experimental work thus far has been carried out on mouse embryos. In our work, we designed experiments to determine whether sheep embryos subjected to inner cell mass (ICM) transfer retain normal developmental competence. In vitro-derived sheep blastocysts (Ptak et al. 2003 Biol. Reprod. 69, 278–285) were manipulated with a Narishige micromanipulator fitted to a inverted Nikon microscope. ICMs were dissected with a blade, and the trophoblastic vesicle and ICMs were cultured in SOFaa plus 10% FCS. After re-expansion, trophoblastic vesicles were injected with ICMs by means of a bevelled pipette and cultured overnight with SOFaa plus 10% FCS. From a total of 35 blastocysts used, 25 re-expanded following injection, and 20 of them showed ICMs adherent to the trophoblast. Seven blastocysts were transferred into synchronized ewes 7 days after estrus, and monitored every month with an Aloka linear probe (7–5 MHz; Aloka Co., Ltd., Tokyo, Japan). Twenty-one in vitro-produced (IVP) embryos were transferred as a control. Three ewes receiving ICM-exchanged blastocysts were pregnant at the first scanning, and all delivered normal offspring (two female and one male lamb; weight: 3.54 ± 0.358 kg). These data demonstrate that dramatic alteration of the blastocyst structure does not compromise its developmental potential. Our efficiency in terms of offspring is lower compared with control IVP embryos, and also compared to data obtained in mice (Papaioannou 1982 J. Embryol. Exp. Morph. 68, 199–209), but technical improvements are expected to reduce such a gap. In conclusion, we demonstrated the feasibility of ICM/trophoblastic exchange in sheep blastocysts; these results might have important application for technologies like somatic cell nuclear transfer (SCNT). Common features of SCNT clones are placental abnormalities in early (DeSousa et al. 2001 Biol. Reprod. 65, 23–30) and late pregnancies (Loi et al. 2006 Theriogenology 65, 1110–1121). The transfer of ICM from cloned embryos to normal trophoblastic vesicles, although ineffective in cattle (Murakami et al. 2006 Cloning Stem Cells 8, 51–69), might be worth trying on sheep, a species where post-natal mortality in clones is a serious issue. Table 1.Development to term of manipulated and cloned embryos Part of this work was supported by EUROSTELLS-European Science Foundation.

Developmental and functional evidence of nuclear immaturity in prepubertal oocytes

BACKGROUND

The nuclear compartment has been proposed as responsible for the developmental arrest of prepubertal mouse oocytes while the studies on prepubertal sheep and cow oocyte model suggested the cytoplasm immaturity accounts for this failure.

METHODS

The apparent disagreement on the causes of developmental defects between these two species prompted us to study: (i) follicular and oocyte growth allometry in lambs, (ii) oocyte compartment (nucleus versus cytoplasm) responsible for developmental failure by nucleus exchange between lamb and adult sheep oocytes, (iii) nucleolar features of prepubertal oocytes by ultrastructural observation and (iv) in vivo developmental survey of prepubertally derived embryos.

RESULTS

The oocyte growth inside the follicle is asynchronous during prepuberty. The nuclear transfer revealed that the lamb nucleus was responsible for developmental failure. Immature fibrillogranular structure of the nucleolus has been revealed in small lamb oocytes and also in a few adult-size lamb oocytes. Studies in vivo revealed a high occurrence of developmental arrest of prepubertal derived fetuses, which we have attributed to the low genome-wide methylation detected in prepubertal oocytes.

CONCLUSIONS

Our studies have indicated incomplete nuclear maturation of prepubertal gamete. The implication of this finding suggests caution when the strategy of rescue of prepubertal oocytes for assisted fertilization is considered such as in the case of therapeutic treatment which precludes the maintenance of fertility of sexually immature patients.

Leukaemia inhibitory factor enhances sheep fertilization in vitro via an influence on the oocyte

LIF is twice transiently expressed in the mouse uterus, first at the time of ovulation and again just prior to implantation, and studies have demonstrated a beneficial influence of this cytokine on embryo development in several species. We have investigated the effect of LIF on gametes in vitro, on the hypothesis that the ovulatory peak of LIF can exert an influence on gametes present within the oviduct. We also investigated the effect of LIF on in vitro fertilization and embryo development, in oocytes from adult sheep and from prepubertal lambs that lack the preovulatory hormone surge and that are unable to sustain early embryonic development. A higher rate of pronuclear-stage embryos derived from both, adult and prepubertal female, was obtained when in vitro fertilization was performed in the presence of LIF, and there was an improved cleavage of parthenogenetic embryos when incubated with LIF immediately following activation. In contrast, LIF was found to have no influence on the viability of ram semen. In vitro fertilized two-cell stage embryos from adult sheep and prepubertal lambs, cultured in defined medium enriched with LIF, both reached the blastocyst stage at similar rates to control embryos. However, LIF exerted a positive influence on the quality of the blastocysts as revealed by significantly higher number of ICM cells and total number of cells. Together, these data demonstrate that LIF exerts a beneficial effect on sheep oocytes and embryos in vitro, but only at stages concomitant with steroid hormones surges.

179 EFFECTS OF AN ENDOCANNABINOID, ANANDAMIDE, ON BOVINE BLASTOCYST DEVELOPMENT IN VITRO

Cannabinoids cause many adverse effects on reproductive functions including fetal loss and pregnancy failure (Paria et al. 1995 PNAS 92, 9460–9464). N-arachidonylethanolamine (anandamide), an endogenous cannabinomimetic lipid derivative, binds with high affinity to brain type and spleen type cannabinoid receptors (CB1-R and CB2-R) and mimics most of the effects of Δ9-tetrahydrocannabinol [(−)THC], a psychoactive derivative of marijuana. In this study, we investigated the effects of anandamide on ovine blastocyst development in vitro. In vitro-matured oocytes were chemically activated and cultured to the blastocyst stage in our standard media (Ptak et al. 1999 Biol. Reprod. 61, 1568–1574). The development rate of blastocysts was 41%. Day 7 blastocysts were exposed to 28 nM anandamide with or without 20 nM SR141716A (an antagonist of CB1-R) for 48 h. In Experiment 1, we examined the CB1-R protein localization on blastocysts by anti CB1-R antibody (Santa Cruz Biotechnology, Inc., Santa Cruz, CA, USA). In Experiment 2, to investigate the possible effect of anandamide on blastocyst development, we used the cell viability assay by propidium iodide, a cell proliferation assay (5-bromo-1′-deoxyuridine incorporation), and the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assay (Qbiogene, Inc., Carlsbad, CA, USA). Data were analyzed by one-way ANOVA. CB1-R signals were detected on ovine blastocysts, and these signals were effectively improved in the anandamide co-cultured group. The results of Experiment 2 are summarized in Table 1. Our results demonstrate that CB1-R was expressed in the ovine blastocyst, and anandamide exerts negative effects on in vitro blastocyst development by inhibiting cell proliferation and increasing apoptotic rate, but not cell viability. Furthermore, SR141716A can effectively block the negative effects of anandamide. Table 1. Effect of anandamide (AEA) on sheep blastocyst development assessed by viability, cell proliferation, and TUNEL staining assays

57 DEFECTIVE PLACENTAL VASCULARIZATION AND TROPHISMS IN FULL TERM SOMATIC CELL SHEEP CLONES

We report on cloning experiments designed to explore the causes of peri- and post-natal mortality of cloned lambs. A total of 93 blastocysts obtained by nuclear transfer of somatic cells (granulosa cells) were transferred into 41 recipient ewes, and pregnancies were monitored by ultrasound scanning. In vitro-derived, fertilized embryos (IVF; n = 123) were also transferred in order to assess oocyte competence; naturally mated ewes (n = 120) were analyzed as well. Cloned embryos developed to the blastocyst stage and implanted at the same rate as IVF embryos. After Day 30 of gestation, however, dramatic losses occurred, and only 12 out of 93 (13%) clones reached full-term development, compared to 51 out of 123 (41.6%) lambs born from the IVF control embryos. Three full-term lamb clones were delivered stillborn as a result of placental degeneration. A further five clone recipients developed hydroallantois. Their lambs died within 24 h following delivery by Caesarean section; their carcasses displayed degenerative lesions in liver and kidney resulting from the severe hydroallantois. One set of twins was delivered by assisted parturition at Day 150, but died 24 h later due to respiratory distress syndrome. The remaining two clone recipients underwent Caesarean section; the corresponding two lambs displayed signs of respiratory dysfunction and died at approximately one month of age due to a bacterial complication. Blood samples collected from the cloned lambs after birth revealed a wide range of abnormalities indicative of kidney and liver dysfunction. Macroscopical and histopathological examination of the placentae revealed a marked reduction in vascularization, particularly at the apex of the villous processes, as well as a loss of differentiation of the trophoblastic epithelium. Our results strongly suggest that post-mortality in cloned lambs is mainly caused by placental abnormalities.

Noninvasive evaluation of cardiac output during postural change and exercise in humans: comparison between the modelflow and pulse dye-densitometry

To investigate whether the Model-flow method, by simulating the aortic input impedance model from a noninvasive monitoring of arterial blood pressure, reflected a reliable measure of cardiac output (CO) during postural change and whole-body exercise occurring in daily life, we compared the Modelflow-estimated CO with a simultaneous reference determined by the pulse dye-densitometry. Nine healthy volunteers performed postural change from supine to upright and dynamic stepping exercise. The Modelflow-estimated CO decreased to 4.8 +/- 0.5 l/min, from 5.8 +/- 0.6 l/min, during the postural change and increased to 12.8 +/- 1.3 l/min during a stepping exercise, returning to 5.1 +/- 0.4 l/min at 5 min after exercise. When comparing the pooled data of CO during resting and following exercise between the Modelflow and pulse dye-densitometry, we found that the average CO did not differ between the two estimates and that there was a significant correlation between them; the slope of the linear regression line corresponded to approximately 1.0. Although such linear relationship was also observed in an individual subject, the slope of the regression line varied from 0.737 to 1.588 among the subjects. The calibration of the Modelflow-estimated CO with the dye-densitometry value at supine or upright improved a correlation between the two estimates. Thus it is likely that the noninvasive Modelflow simulation from arterial blood pressure can provide a reliable estimation of group-average cardiac output during postural change and stepping exercise occurring in daily life. It will be recommended for a more accurate estimation of cardiac output in a given subject to calibrate the Modelflow data with an independent measure.

Developmental potential of bovine nuclear transfer embryos and postnatal survival rate of cloned calves produced by two different timings of fusion and activation

We compared developmental potential of somatic cell nuclear transfer (NT) embryos and postnatal survivability of cloned calves produced by two different fusion and activation protocols. As donor cells for NT, bovine cumulus cell-derived cultured cells of passage 5 were used following culture in serum-starved medium for 5-7 days. Enucleated oocytes were fused with donor cells at 21 or 24 hr post maturation. NT embryos fused at 21 hr were activated chemically 3 hr after fusion (DA group) and embryos fused at 24 hr were activated chemically immediately after fusion (FA group). Chemical activation was accomplished by calcium ionophore for 5 min and cytochalasin D + cycloheximide for 1 hr then cycloheximide alone for 4 hr. After in vitro culture in IVD101 medium for 7 days, embryo transfer was performed. Fusion rates were 86 and 84% in the DA and FA groups, respectively. Developmental rate to the blastocyst stage of NT embryos in the DA group was higher than in the FA group (42% vs. 28%). Pregnancy rate did not differ significantly between the DA and FA groups (11/13 and 5/7 at day 35), and 13 cloned calves (including 1 set of twins from a single embryo transfer) were born. High rates of postnatal mortality were observed in both groups. These results suggest that the DA method improves in vitro developmental potential of NT embryos, but the timing of fusion and chemical activation does not affect the pregnancy rate and the survivability of cloned calves.

Reflex responses in plasma catecholamines caused by static contraction of skeletal muscle

To examine a hypothesis of whether static muscle contraction produces a release of catecholamines from the adrenal medulla via reflex stimulation of preganglionic adrenal sympathetic nerve activity induced by receptors in the contracting muscle, we compared the reflex responses in a concentration of epinephrine (Ep) and norepinephrine (NEp) in arterial plasma during static contraction and during a mechanical stretch of the hindlimb triceps surae muscle in anesthetized cats. Static contraction was evoked by electrically stimulating the peripheral ends of the cut L(7) and S(1) ventral roots at 20 or 40 Hz. Mean arterial pressure (MAP) and heart rate (HR) increased 23 +/- 3.1 mmHg and 19 +/- 4.3 beats/min during static contraction. Ep in arterial plasma increased 0.18 +/- 0.072 ng/ml over the control of 0.14 +/- 0.051 ng/ml within 1 min from the onset of static contraction, and NEp increased 0.47 +/- 0.087 ng/ml over the control of 0.71 +/- 0.108 ng/ml. Following a neuromuscular blockade, although the same ventral root stimulation failed to produce the cardiovascular and plasma catecholamine responses, the mechanical stretch of the muscle increased MAP, HR, and plasma Ep, but not plasma NEp. With bilateral adrenalectomy, the baseline Ep became negligible (0.012 +/- 0.001 ng/ml) and the baseline NEp was lowered to 0.52 +/- 0.109 ng/ml. Neither static contraction nor mechanical stretch produced significant responses in plasma Ep and NEp following the adrenalectomy. These results suggest that static muscle contraction augments preganglionic adrenal sympathetic nerve activity, which in turn secretes epinephrine from the adrenal medulla into plasma. A muscle mechanoreflex from the contracting muscle may play a role in stimulation of the adrenal sympathetic nerve activity.

Cardiac vagal and sympathetic efferent discharges are differentially modified by stretch of skeletal muscle

We directly measured cardiac vagal efferent nerve activity (CVNA) and cardiac sympathetic efferent nerve activity (CSNA) in cats decerebrated at the level of the precollicular-premammillary body while the hindlimb or the triceps surae muscle was passively stretched. CVNA gradually decreased during passive stretch of the hindlimb, and this decrease was sustained throughout the stretch. CSNA increased at the onset of passive stretch, but this increase was not sustained. CVNA and CSNA responded differentially to graded passive stretches of the triceps surae muscle as well as the hindlimb. The sustained decrease in CVNA but not the initial increase in CSNA became greater depending on muscle length and developed tension. The time course and direction of the cardiac autonomic responses to muscle stretch were not affected by partial sinoaortic denervation, although the magnitude of the CSNA response was augmented. We conclude that the muscle mechanoreflex contributes to differential regulation of cardiac parasympathetic and sympathetic efferent discharges during passive stretch of skeletal muscle irrespective of arterial baroreceptor input.

Effect of renal denervation on the compensatory renal growth following nephrectomy in the cat

The purpose of this study was to clarify the effect of denervation on the mass of the remaining kidney with or without unilateral nephrectomy using adult cats. The animals were divided into 4 groups: (1) control group, the weights of the right and left kidneys were measured intact in 5 cats; (2) nephrectomy group (Nx, n = 5 cats), the right kidney was removed and the left kidney was weighed 3-5 d after nephrectomy; (3) nephrectomy and denervation group (Nx+Dx, n = 7 cats), the left kidney was weighed on the 7th day after surgery in which the left kidney was denervated and the right kidney was removed; and (4) denervation group (Dx+Dx, n = 5 cats), both kidneys were weighed on the 7th day after denervation of the kidneys. In the control group, the left and right kidney weights per body weight (LKW and RKW) were the same (LKW, 0.74 +/- 0.06%; RKW, 0. 74 +/- 0.07%). In the Nx group, LKW increased to 0.90 +/- 0.03% 3-5 d after nephrectomy, although RKW of the removed kidney was 0.66 +/- 0.01%. In the Nx+Dx group, LKW increased to 0.97 +/- 0.15%, which was similar to that of the Nx group. In the Dx+Dx group, LKW (0.56 +/- 0.05%) and RKW (0.54 +/- 0.05%) were significantly less than those in the control group. We conclude that the renal nerves may contribute to maintaining the renal mass and that the neural effect on compensatory growth following nephrectomy may be covered by other growth factors.

Effects of mental stress on cardiac and motor rhythms

To identify whether spontaneous cardiac rhythm and voluntary motor rhythm are modified in parallel or influenced separately when imposing mental stress, we recorded simultaneously the two rhythms during finger tapping as a simple model of rhythmical motion in 10 healthy human subjects (6 males, 4 females each). Each subject performed finger tapping with an arbitrary tapping rhythm. Mental stress was given intermittently three times for 10-15 s at intervals of 40 s during tapping for 150 s. Heart rate (HR) and tapping rate (TR) and their variations (standard deviation; SD) during finger tapping with and without mental stress were compared. HR and TR increased significantly in response to mental stress during tapping. After mental stress was ended, HR returned rapidly to the initial level, but TR remained at a higher level. Moreover, SD of TR, but not SD of HR, during tapping was increased by mental stress. The present results indicate that the cardiac and motor rhythms are influenced simultaneously by mental stress. However, a difference was seen about the sustained effect of mental stress on the two rhythms.

Augmented renal sympathetic nerve activity by central command during overground locomotion in decerebrate cats

We examined whether the cerebrum is essential for producing the rapid autonomic adjustment at the onset of spontaneous overground locomotion. Renal sympathetic nerve activity (RSNA), mean arterial pressure (MAP), heart rate (HR), and electromyogram of the forelimb triceps brachialis were measured when freely moving, decerebrate cats spontaneously produced overground locomotion, supporting body weight. Decerebration was performed at the level of the precollicular-premammillary body. RSNA increased 95 +/- 14 impulses/s (68 +/- 10% of baseline value) at the onset of spontaneous locomotion, which was followed by rises in MAP and HR (7 +/- 1 mmHg and 18 +/- 2 beats/min, respectively). Concomitantly with the MAP rise, RSNA declined toward control values and then increased again during the subsequent period of locomotion. The same rapid increase in RSNA at the onset of locomotion was observed after sinoaortic denervation and vagotomy. It is concluded that some central site(s), other than the cerebrum and the rostral part of the diencephalon, can generate the centrally induced autonomic adjustment at the onset of spontaneous overground locomotion, which is independent of arterial baroreceptor and vagal afferents.

Cardiovascular responses during spontaneous overground locomotion in freely moving decerebrate cats

To examine whether the cerebrum is essential for producing the rapid cardiovascular adjustment at the beginning of overground locomotion, we examined heart rate (HR), mean arterial blood pressure (MAP), and integrated electromyogram (iEMG) of the forelimb triceps brachialis muscle in freely moving decerebrate cats during locomotion. Two to four days after decerebration surgery performed at the level of the precollicular-premammillary body, the animals spontaneously produced coordinated overground locomotion, supporting body weight. HR began to increase immediately before the onset of iEMG, and MAP began to rise almost simultaneously with the iEMG onset. Their increases in HR and MAP (24 +/- 3 beats/min and 22 +/- 4 mmHg) were sustained during locomotion. Sinoaortic denervation (SAD) did not affect the abrupt changes in HR and MAP at the beginning of locomotion (0-4 s from the onset of iEMG), whereas SAD had a contrasting effect during the subsequent period, a decrease in the HR response (9 +/- 1 beats/min) and an increase in the MAP response (30 +/- 3 mmHg). These results suggest that the cerebrum and the rostral part of the diencephalon are not essential for producing the rapid cardiovascular adjustment at the beginning of spontaneous overground locomotion. The arterial baroreflex does not contribute to this rapid adjustment but plays an important role in regulating the cardiovascular responses during the later period of spontaneous locomotion.

Direct observations of sympathetic cholinergic vasodilatation of skeletal muscle small arteries in the cat

1. The aim of this study was to examine the actual changes of the internal diameter (i.d.) of arterial vessels of skeletal muscle evoked by activation of sympathetic cholinergic nerve fibres during stimulation of the hypothalamic defence area in anaesthetized cats. 2. For this purpose, we have used our novel X-ray TV system for visualizing small arteries (100-500 microm i.d.) of the triceps surae muscle and larger extramuscular arteries (500-1400 microm i.d.) of the hindlimb (the femoral (FA), popliteal (PA) and distal caudal femoral (DCFA) arteries). The passage of a contrast medium from the large extramuscular arteries to the smaller intramuscular arteries was serially measured before and during hypothalamic stimulation. 3. Hypothalamic stimulation increased mean arterial blood pressure, heart rate and femoral vascular conductance. The i.d. of FA, PA, and DCFA did not change during the hypothalamic stimulation, whereas the i.d. of small arteries in the triceps surae muscle increased by 48 +/- 2% (mean +/- S.E.M.) and the cross-sectional area increased concomitantly by 118%. The maximum increase in i.d. of 78 +/- 6%, was observed in arteries of 100-200 microm. These increases in diameter were markedly reduced by intra-arterial injection of atropine or by cutting the sciatic nerve, but not by phentolamine and propranolol given together. 4. The vasodilatation evoked by hypothalamic stimulation was seen in almost all the sections of the small arteries observed under control conditions and was distributed along the entire length of the vessel. In addition, the number of arterial vessels that could be detected increased by 42% during hypothalamic stimulation. The newly detected arterial branches, which ranged from 100 to 300 microm in diameter, mostly arose from the branching points. 5. It is concluded that stimulation of sympathetic cholinergic nerve fibres dilates the small arteries of skeletal muscle ranging from 100 to 500 microm, but not the larger extramuscular arteries.

Tissue distribution of human gliostatin/platelet-derived endothelial cell growth factor (PD-ECGF) and its drug-induced expression

Human tissue contents of gliostatin/platelet-derived endothelial cell growth factor (PD-ECGF) and its drug-induced expression in tumor cells were currently examined by a sandwich enzyme immunoassay (EIA) system and a reverse transcription-polymerase chain reaction (RT-PCR) method. Gliostatin/PD-ECGF was found to distribute in rather ubiquitous than specific human tissues and organs, with a relatively high levels in the tissues of digestive system (esophagus and rectum), brain, spleen, bladder and lung, but not in gall bladder, aorta, muscle, fat and kidney. Most of examined human tumor cell lines showed 4- or 5-fold higher contents (21.5 +/- 3.9 ng/mg protein) than normal tissue contents (4.4 +/- 1.1 ng/mg protein) on the average. While gliostatin/PD-ECGF is known to lack a signal sequence, some tumor cells (A431 and MKN74) appeared to release it into the conditioned medium. Expression of gliostatin/PD-ECGF in epidermoid carcinoma cell (A431) and stomach cancer cell (MKN45) was induced by dibutyryl cyclic AMP and phorbol ester, and uniquely in MKN45 by hydrocortisone. In particular, this hydrocortisone specifically caused an increase of the apparent secretion of MKN74 without its cytotoxic effects, suggesting a possible secretion of gliostatin/PD-ECGF in the restricted but not universal cell line. Biological significance on the chemical induction of gliostatin/PD-ECGF in tumor cells and on its extracellular secretion are discussed.

Divergence of ventilatory responses to isometric contraction in anesthetized cats

The purpose of this study was to determine if the initial ventilatory and phrenic nerve responses to isometric contraction of the triceps surae muscle of anesthetized cats are influenced by the pattern of the contraction. To address this, three different types of muscle contraction were evoked: (1) a high tension, continuous tetanic (HT-CT) contraction; (2) a moderate tension, continuous tetanic (MT-CT) contraction; and (3) high tension, intermittent tetanic (HT-IT) contractions. The duration of each contraction period was 60 sec. The MT-CT and HT-IT contractions increased minute volume (VE; 19 +/- 4% and 15 +/- 5%, respectively) within the first 15 sec. These increases were the result of rises in breathing frequency and tidal volume. However, only the MT-CT contraction increased phrenic activity (pVE) in the first 15 sec. By contrast, ventilation and phrenic nerve activity failed to increase within the first 15 sec of the HT-CT contraction. If fact, 'tidal' phrenic activity (pVT; -14 +/- 5%) decreased during the first 5 sec, and there was a tendency for tidal volume (VT; -8 +/- 5%), VE (-8 +/- 6%), and pVE (-16 +/- 8%) to fall. These data suggest that stimulation of muscle afferent fibers by static contraction can initially inhibit phrenic nerve activity, provided the activation is sustained and of sufficient intensity.