Christopher M. Fredericks

Characterization of the oxybutynin antagonism of drug-induced spasms in detrusor.

Oxybutynin chloride exerts a moderate anticholinergic effect on rabbit detrusor in vitro, which is reversible and competitive in nature (KB = 4.7 x 10(-9), and midway in potency between atropine and papaverine. In addition, oxybutynin strongly antagonizes BaCl2-induced spasms of detrusor with a potency equivalent to that of papaverine and 10 times that of atropine. This musculotropic spasmolytic effect is slightly greater in rabbit than human or monkey tissue, and noncompetitive (pD2 = 5.5). This direct relaxant effect, unlike that of papaverine, is not mediated by the inhibition of tissue phosphodiesterase, but probably reflects oxybutynins local anesthetic properties and associated effects on Ca++ fluxes and binding.

Effect of vasoactive intestinal polypeptide (VIP) on the in vitro and in vivo motility of the rabbit reproductive tract

Isolated segments of rabbit ampulla and isthmus and strips of uterus and cervix were spontaneously mechanically active in vitro, and this activity was inhibited in a dose-dependent manner by 2 to 200 ng/ml vasoactive intestinal polypeptide (VIP). The oviductal segments were the most inhibited, the uterine strips the least inhibited. These tissues were stimulated to contract in a dose-dependent manner by epinephrine (EPI), with the uterus and cervix being the more responsive. VIP (200 ng/ml) produced only a slight noncompetitive antagonism of this stimulation. Recordings made with miniature force transducers showed the isthmus, uterus, and cervix also to be spontaneously active in vivo. This activity was inhibited by injections (1, 10, and 20 micrograms) and infusions (1.0 and 2.5 micrograms/min) of VIP. The isthmus was the most inhibited, the cervix the least inhibited. Possible physiologic implications of these pharmacologic effects are discussed.

Sperm and seminal plasma antigens from autoimmune men induce immunological infertility

Adult male rabbits were immunized with normal saline (controls), sperm extracts from 2 autoimmune men, seminal plasmas from the same autoimmune men, sperm extract from a fertile nonautoimmune man, and seminal plasma from the same fertile nonautoimmune man. All the sperm donors were free from infections. Rabbits immunized with fertile mens sperm extract and seminal plasma had significantly elevated postimmunization hemagglutinating but not cytotoxic sperm antibodies and reproduced normally. Rabbits immunized with autoimmune mens sperm and seminal plasma antigens developed high titers of cytotoxic and hemagglutinating sperm antibodies in their serum and seminal plasma and their reproduction was markedly reduced. Their sera and seminal plasma reduced motility of sperm from a normal donor. The immune responses were confirmed by electron microscopic immunocytochemistry. This technique revealed membrane-bound endogenous IgG on sperm from only those rabbits immunized with sperm extracts from autoimmune men. These antisera reacted against a protein in the 58,000 D range; antisera to fertile mans sperm extract reacted against three proteins with molecular weights of 15,000, 18,400, 25,000, and 44,000 D, as judged by Western blot. Rabbit antisera to seminal plasma from autoimmune men reacted against several proteins; additionally, it detected two proteins with 43,000 and 68,000 molecular weight detected by antiserum to fertile mans seminal plasma. Sperm and seminal plasma antigens from autoimmune men are different in their elicited immunogenic responses from those of fertile nonautoimmune men. These responses are relevant to infertility.

Physiological Integrity of Human Sperm in the Presence of Ureaplasma Urealyticum

Several species of Mycoplasma have been isolated from the human genital tract, the most common being M. hominis and Ureaplasma urealyticum. A causal relationship between such infections and sperm dysfunction and infertility has yet to be established. It was the purpose of this study to examine the effects of U. urealyticum infection on the function of sperm as assessed by seminal fluid analysis (SFA), in vitro penetration of bovine cervical mucus (BCMP), and the hamster sperm penetration assay (SPA). No significant differences were noted in the SFA of infected and uninfected samples, either fresh or frozen, fertile or infertile. In addition, no differences were noted in the BCMP or SPA. In sperm from U. urealyticum-infected individuals the basic physiological mechanisms underlying mucus penetration and ovum fertilization seem intact.

Vasoactive intestinal polypeptide stimulates nonovarian progesterone secretion in rabbits

Recent experiments conducted in this laboratory have shown that intravenous infusions of vasoactive intestinal polypeptide (VIP) induced significant increases in plasma progesterone (P) in female rabbits. The purpose of this study was to determine the organ source of this P and to clarify the mechanisms by which it is induced. Intravenous infusions of VIP (37.5, 75, and 150 pmol/kg per min for 60 min) produced acute dose-dependent increases in plasma P in intact estrous rabbits. In ovariectomized (OVX) animals, VIP infusion (75 pmol/kg per min) produced a P increase of the same magnitude. In animals both OVX and adrenalectomized (ADX), this VIP effect was eliminated. The only significant change noted in luteotropic hormone (LH) or follicle stimulating hormone (FSH) was a decrease in FSH immediately following VIP infusion (150 pmol/kg). VIP infusion significantly increased plasma cortisol in intact and OVX animals, but not in OVX/ADX animals. It is concluded that VIP primarily stimulates the adrenal component of P secretion in the rabbit, via mechanisms independent of LH or FSH.

Relationship Between the Sperm Penetration Assay and Other Tests of Sperm Function

Semen from 88 men of infertile couples and 33 fertile donors differed in seminal fluid analysis (sperm density and motility) (SFA) as well as in the penetration of hamster ova (SPA) and bovine cervical mucus (MPT). In the fertile group, significantly more subjects had adequate SFA, SPA, or MPT results than in the infertile group. When the two groups were subdivided into those with normal or those with abnormal SFA, no differences were noted in SPA, MPT, or postcoital test (PCT) scores. The SFA parameter most consistently reflected in the results of the SPA, MPT, and PCT was sperm density. This was most evident when the SFA was poor. The worst prognosticator of fertility was the SFA, with 30% of the fertile donors having an abnormal SFA. The worst prognosticator of infertility was the MPT, with 79% of the patients penetrating in the fertile range. The SPA was a significantly better predictor than either the SFA or MPT. SPA and MPT results were positively correlated only in the overall infertile group. The SPA, MPT, and PCT measure sperm qualities distinct from those revealed by the SFA, and from each other, and in combination provide the best assessment of fertility.

A Miniature Extraluminal Force Transducer for Recording In Vivo Oviductal Motility

A miniature extraluminal force transducer has been developed and used to record acute and chronic motility of the reproductive tract in the rabbit. This device, which contains two matched piezoresistive silicon sensors bonded to a titanium beam strip, is durable, physically stable, and highly sensitive to bending force (gage factor, 140). Acute recordings made in 20 rabbits revealed continuous, rhythmic contractile activity in both the oviduct and uterus. Chronic recordings made in three unanesthetized rabbits revealed periodic bursts of intense activity interspersed with periods of relative quiescence. Chronic implantation of these devices was accomplished with no evidence of infection, adhesions, or other abnormalities, and without disruption of fertility.

The Effect of Transection of the Accessory Ligaments on Reproduction in the Rabbit**Supported in part by South Carolina 1977–1978 State Appropriation for Biomedical Research.

The mesotubarium superius (MTS) and uterovarian ligament (UOL) contain smooth muscle, are mechanically active, and have been implicated in ovum transport in a number of species. To assess the reproductive importance of these ligaments, they were unilaterally transected in 27 rabbits and the effects on reproduction determined. Reproductive function was characterized in terms of the numbers of corpora lutea, uterine implants, and normal conceptuses resulting from breeding with fertile bucks. Fertility was defined by the proportion of ovulating follicles resulting in implantation and normal conceptuses. Grouped and paired sample analyses of these data showed no differences between the experimental and control sides of the reproductive tracts of animals in which the UOL, MTS, or both were transected. The structural integrity of these ligaments is thus not necessary for normal conception and fertility in the rabbit.