An electrophysiologic study of female ejaculation

Biophysical Mechanisms of Vaginal Smooth Muscle Contraction: The Role of the Membrane Potential and Ion Channels

The vagina is an essential component of the female reproductive system and is responsible for providing female sexual satisfaction. Vaginal smooth muscle contraction plays a crucial role in various physiological processes, including sexual arousal, childbirth, and urinary continence. In pathophysiological conditions, such as pelvic floor disorders, aberrations in vaginal smooth muscle function can lead to urinary incontinence and pelvic organ prolapse. A set of cellular and sub-cellular physiological mechanisms regulates the contractile properties of the vaginal smooth muscle cells. Calcium influx is a crucial determinant of smooth muscle contraction, facilitated through voltage-dependent calcium channels and calcium release from intracellular stores. Comprehensive reviews on smooth muscle biophysics are relatively scarce within the scientific literature, likely due to the complexity and specialized nature of the topic. The objective of this review is to provide a comprehensive description of alterations in the cellular physiology of vaginal smooth muscle contraction. The benefit associated with this particular approach is that conducting a comprehensive examination of the cellular mechanisms underlying contractile activation will enable the creation of more targeted therapeutic agents to control vaginal contraction disorders.

Smooth muscle contribution to vaginal viscoelastic response

Smooth muscle cells contribute to the mechanical function of various soft tissues, however, their contribution to the viscoelastic response when subjected to multiaxial loading remains unknown. The vagina is a fibromuscular viscoelastic organ that is exposed to prolonged and increased pressures with daily activities and physiologic processes such as vaginal birth. The vagina changes in geometry over time under prolonged pressure, known as creep. Vaginal smooth muscle cells may contribute to creep. This may be critical for the function of vaginal and other soft tissues that experience fluctuations in their biomechanical environment. Therefore, the objective of this study was to develop methods to evaluate the contribution of smooth muscle to vaginal creep under multiaxial loading using extension - inflation tests. The vaginas from wildtype mice (C57BL/6 × 129SvEv; 3-6 months; n = 10) were stimulated with various concentrations of potassium chloride then subjected to the measured in vivo pressure (7 mmHg) for 100 s. In a different cohort of mice (n = 5), the vagina was stimulated with a single concentration of potassium chloride then subjected to 5 and 15 mmHg. A laser micrometer measured vaginal outer diameter in real-time. Immunofluorescence evaluated the expression of alpha-smooth muscle actin and myosin heavy chain in the vaginal muscularis (n = 6). When smooth muscle contraction was activated, vaginal creep behavior increased compared to the relaxed state. However, increased pressure decreased the active creep response. This study demonstrated that extension - inflation protocols can be used to evaluate smooth muscle contribution to the viscoelastic response of tubular soft tissues.

Sexual incentive motivation, sexual behavior, and general arousal: Do rats and humans tell the same story?

Sexual incentive stimuli activate sexual motivation and heighten the level of general arousal. The sexual motive may induce the individual to approach the incentive, and eventually to initiate sexual acts. Both approach and the ensuing copulatory interaction further enhance general arousal. We present data from rodents and humans in support of these assertions. We then suggest that orgasm is experienced when the combined level of excitation surpasses a threshold. In order to analyze the neurobiological bases of sexual motivation, we employ the concept of a central motive state. We then discuss the mechanisms involved in the long- and short-term control of that state as well as those mediating the momentaneous actions of sexual incentive stimuli. This leads to an analysis of the neurobiology behind the interindividual differences in responsivity of the sexual central motive state. Knowledge is still fragmentary, and many contradictory observations have been made. Nevertheless, we conclude that the basic mechanisms of sexual motivation and the role of general arousal are similar in rodents and humans.

Female ejaculation: An update on anatomy, history, and controversies

Female ejaculation is a contentious topic. From a review of the literature, history indicates that it is not a modern concept; some females were aware of it in times past without understanding the role of the fluid or composition of the ejaculate. Over time, scholars experimented, mainly with anatomical studies, in an attempt to identify the source of the ejaculate and explore its physiological and anatomical benefits for the female sexual experience. Despite these studies, views about female ejaculation remain controversial and inconsistent, with no clear conclusion as to its function. This review discusses the history of studies of female ejaculation and presents various hypotheses from an anatomical and physiological perspective. After reviewing 44 publications from 1889 to 2019, it became apparent that clinical and anatomical studies conducted during recent decades provide substantial evidence in support of the female ejaculatory phenomenon. Anatomical studies have shown that the ejaculate originates in the paraurethral (Skene's) glands, but its composition has been debated. Female ejaculate differs from urine in its creatinine and urea concentrations. The fluid also contains prostate specific antigen (PSA) and could have antibacterial properties that serve to protect the urethra. While the specific function of female ejaculation remains a topic of debate, there is sufficient evidence to support the existence of the phenomenon.

Devices and Methods to Measure Female Sexual Arousal

INTRODUCTION

Multiple methods and devices are available for the assessment of female sexual response, each with strengths and limitations that can impact interpretation of research results. As such, it is important to have an understanding of available methodologies and instruments.

AIM

To review recent literature on the measurement of female sexual response, and to describe the methods and devices, and their strengths and limitations.

METHODS

A literature review was performed regarding methodology and instruments used to quantify female sexual response.

MAIN OUTCOME MEASURES

The description of currently available instruments and methods to quantify sexual response in women.

RESULTS

Methodologies used to examine female sexual arousal employ a variety of stimuli and instruments to elicit and record sexual response. The variation in research designs across studies highlights the importance of understanding (i) how sexual response is elicited in studies; (ii) what kinds of experimental designs are available for assessing sexual psychophysiology; and (iii) the various types of instrumentation used to collect data.

CONCLUSIONS

The physiological and self-reported measurement of female sexual response is crucial to our understanding of the mechanisms and factors involved with healthy sexual functioning. As such, it is important to understand the strengths and limitations associated with different stimuli, research designs, and instruments. Kukkonen TM. Devices and methods to measure female sexual arousal.

Female ejaculation orgasm vs. coital incontinence: a systematic review

INTRODUCTION

Women may expel various kinds of fluids during sexual arousal and at orgasm. Their origins, quantity, compositions, and expulsion mechanisms depend on anatomical and pathophysiological dispositions and the degree of sexual arousal. These are natural sexual responses but may also represent symptoms of urinary incontinence.

AIM

The study aims to clarify the etiology of fluid leakage at orgasm, distinguish between associated physiological sexual responses, and differentiate these phenomena from symptoms of illness.

METHODS

A systematic literature review was performed. EMBASE (OvidSP) and Web of Science databases were searched for the articles on various phenomena of fluid expulsions in women during sexual arousal and at orgasm.

MAIN OUTCOME MEASURES

Articles included focused on female ejaculation and its variations, coital incontinence (CI), and vaginal lubrication.

RESULTS

Female ejaculation orgasm manifests as either a female ejaculation (FE) of a smaller quantity of whitish secretions from the female prostate or a squirting of a larger amount of diluted and changed urine. Both phenomena may occur simultaneously. The prevalence of FE is 10-54%. CI is divided into penetration and orgasmic forms. The prevalence of CI is 0.2-66%. Penetration incontinence occurs more frequently and is usually caused by stress urinary incontinence (SUI). Urodynamic diagnoses of detrusor overactivity (DOA) and SUI are observed in orgasmic incontinence.

CONCLUSIONS

Fluid expulsions are not typically a part of female orgasm. FE and squirting are two different physiological components of female sexuality. FE was objectively evidenced only in tens of cases but its reported high prevalence is based mostly on subjective questionnaire research. Pathophysiology of squirting is rarely documented. CI is a pathological sign caused by urethral disorder, DOA, or a combination of both, and requires treatment. An in-depth appreciation of these similar but pathophysiologically distinct phenomena is essential for distinguishing normal, physiological sexual responses from signs of illness.

Does the G-spot exist? A review of the current literature

In 1950, Gräfenberg described a distinct erotogenic zone on the anterior wall of the vagina, which was referred to as the Gräfenberg spot (G-spot) by Addiego, Whipple (a nurse) et al. in 1981. As a result, the G-spot has become a central topic of popular speculation and a basis of a huge business surrounding it. In our opinion, these sexologists have made a hotchpotch of Gräfenberg's thoughts and ideas that were set forth and expounded in his 1950 article: the intraurethral glands are not the corpus spongiosum of the female urethra, and Gräfenberg did not report an orgasm of the intraurethral glands. G-spot amplification is a cosmetic surgery procedure for temporarily increasing the size and sensitivity of the G-spot in which a dermal filler or a collagen-like material is injected into the bladder-vaginal septum. All published scientific data point to the fact that the G-spot does not exist, and the supposed G-spot should not be identified with Gräfenberg's name. Moreover, G-spot amplification is not medically indicated and is an unnecessary and inefficacious medical procedure.